Why (B) is right: confirming the causal link directly
A Strengthen explanation from our free library. The question below is original, written for this page. Then the full breakdown: why the right answer is right, and why each wrong answer is wrong.
The question
Restaurants that post calorie counts on their menus sell fewer high-calorie dishes than restaurants that do not. The health department concludes that posting calorie counts causes customers to choose healthier food.
Which one of the following, if true, most strengthens the health department's conclusion?
- Restaurants that post calorie counts tend to be in wealthier neighborhoods.
- Customers at those restaurants say in interviews that the posted numbers changed what they ordered. Correct
- Some restaurants that post calorie counts see no change in orders.
- High-calorie dishes are usually the most profitable items on a menu.
- Health-conscious customers often choose restaurants that post calorie counts.
Why (B) is correct
The department claims a cause: the posted numbers change behavior. Choice (B) is the customers themselves confirming the mechanism. They saw the numbers and ordered differently.
That is direct evidence for the exact causal link the conclusion asserts. Notice how many choices here point the wrong way: (A), (C), and (E) all weaken. On strengthen questions, always check the direction of each answer before falling for a tempting one.
Why the wrong answers are wrong
(A) Reversed: it weakens
This offers an alternative explanation, that wealthier customers eat healthier anyway. That hurts the conclusion, the opposite of what the stem asks for.
(C) Reversed: it weakens
This is evidence against the conclusion. It belongs in a weaken question, not here.
(D) Out of scope
Profit says nothing about what causes customers to order differently. The conclusion is about customer behavior, not restaurant profits.
(E) Reversed: it weakens
This suggests the customers were already different, that the restaurant attracted healthy eaters rather than creating them. That undermines the causal claim instead of supporting it.
Last updated October 12, 2026