How to Solve "Strengthen the Argument" Questions in the Selective Test — Selective online practice for the NSW exam

In the Thinking Skills section of the NSW Selective High School Placement Test, evaluating arguments is one of the most heavily tested domains. Within this category, students frequently encounter questions that ask: "Which of the following, if true, most strengthens the argument above?"

For many students, this is a tricky concept. It is easy to confuse an option that sounds like a good idea with an option that actually repairs the logical structure of the author's argument. To succeed in 2026, students must move beyond reading comprehension and learn to act like a lawyer cross-examining a witness.

Here is the strategic framework for solving these questions, followed by three practice examples to test your skills.

The 3-step strategy for "strengthening" questions

To strengthen an argument, you must first understand how it is built. Every argument has three parts:

The premise (the evidence) — The facts provided in the text.

The conclusion (the point) — What the author is trying to convince you of.

The assumption (the gap) — The unwritten leap of faith the author makes to connect the premise to the conclusion.

The golden rule — The correct answer will almost always do one of two things: it will provide new evidence that proves the conclusion is true in a similar real-world scenario, or it will bridge the gap by proving the author's hidden assumption is correct.

Practice Question 1: The "real-world evidence" argument

The argument — A local town councillor has proposed that the council should install more seating and benches along the main shopping street. She argues that providing places for people to rest will directly increase the profits of the local cafes and retail shops, because shoppers will stay in the area for longer.

Question — Which one of the following, if true, most strengthens the councillor's argument?

A) Benches require regular maintenance and cleaning by council staff.

B) Several other towns in the state that installed street seating reported a 20% increase in local retail sales the following year.

C) Many people who use public benches prefer to bring their own packed lunches from home.

D) The main shopping street already has plenty of rubbish bins and shaded areas.

The answer and explanation

Correct answer: B

Why it strengthens the argument — The councillor's conclusion is a prediction: benches lead to more profit. Option B provides direct, real-world precedent. If this exact strategy worked in similar towns to boost sales, it makes the councillor's prediction much more likely to come true.

Why the others are wrong

A — Weakens the argument by introducing a negative cost (maintenance).

C — Heavily weakens the argument; if people bring their own food, they won't spend money at the local cafes.

D — Irrelevant to the core logic of benches increasing sales.

Practice Question 2: The "bridging the assumption" argument

The argument — The school principal wants to introduce a mandatory 15-minute period of silent reading at the beginning of every school day. She argues that this initiative will improve the students' overall academic performance across all subjects, because it will allow them to calm down and focus their minds before their first formal lesson begins.

Question — Which one of the following, if true, most strengthens the principal's argument?

A) Many students prefer to use the morning period to catch up with their friends before class.

B) Reading fiction has been proven to help primary school students expand their vocabulary.

C) A recent educational study demonstrated that students who engage in a quiet, focused activity before learning score significantly higher on afternoon exams.

D) The school library currently does not have enough books for every student to borrow one at the same time.

The answer and explanation

Correct answer: C

Why it strengthens the argument — The principal's assumption is that calming down in the morning directly translates to better academic performance. Option C explicitly bridges this gap. It provides scientific evidence linking the exact proposed action (quiet, focused activity) to the desired outcome (higher exam scores).

Why the others are wrong

A — Weakens the argument by showing that students might resist the silent period.

B — A classic distractor. While building vocabulary is a good thing, the principal's argument is about calming down to improve overall focus, not just getting better at English.

D — Highlights a practical hurdle, which weakens the feasibility of the plan.

Practice Question 3: The "eliminating alternate causes" argument

The argument — The city government should completely ban the sale of single-use plastic water bottles in the CBD to reduce plastic litter. Since the city installed 50 new free, filtered water fountains last month, residents and tourists will easily be able to refill their own reusable bottles instead of purchasing plastic ones.

Question — Which one of the following, if true, most strengthens the government's argument?

A) A recent survey showed that the primary reason people buy plastic water bottles in the CBD is the lack of clean, cold public drinking facilities.

B) Manufacturing a reusable metal water bottle requires significantly more energy than producing a single-use plastic bottle.

C) Plastic bottles currently make up over 30% of the total litter found in the city's parks and waterways.

D) The government intends to impose heavy fines on any retail shops caught selling plastic water bottles after the ban is implemented.

The answer and explanation

Correct answer: A

Why it strengthens the argument — The government's plan assumes that if fountains exist, people will actually use them. Option A confirms this assumption. By stating that the only reason people were buying plastic was a lack of facilities (which have now been provided), it removes the main obstacle to the plan's success, strongly supporting the conclusion that the ban will work.

Why the others are wrong

B — Introduces an environmental negative to reusable bottles, slightly weakening the overall green intent.

C — Another distractor; it provides context on why the litter is a problem, but it doesn't strengthen the logic that the fountains will solve the problem.

D — Addresses enforcement, but it doesn't strengthen the core reasoning that the public will willingly switch to the fountains.

The final takeaway for 2026

When practising these questions, encourage your child to play devil's advocate. Before looking at the A, B, C, D options, ask them: What is the weakest part of this argument? If they can spot the logical gap on their own, finding the option that fixes it becomes a much faster and more accurate process.

Hungry for more "strengthen the argument" reps under real pressure? Isolate those stems on GoTestPrep Thinking Skills until naming the gap—before peeking at options—feels automatic rather than lucky.