A system-wide county school anti-smoking education program was institu

A system-wide county school anti-smoking education program was instituted last year. The program was clearly a success. Last year, the incidence of students smoking on school premises decreased by over 70 percent.

Which of the following, if true, would most seriously weaken the argument in the passage?

(A) The author of this statement is a school system official hoping to generate good publicity for the anti-smoking program.
Incorrect - this does not necessarily mean that the official falsified data.

(B) Most students who smoke stopped smoking on school premises last year continued to smoke when away from school.
Incorrect - this statement is a bit neutral. It neither strengthens the argument nor necessarily weakens it. Furthermore, if the ultimate goal of the program was to decrease on school incidences, then it was still a success.

(C) Last year, another policy change made it much easier for students to leave and return to school grounds during the school day.
Correct - We needed something that indicated another motivation outside of the program. This fulfills that necessity and weakens the argument. If we can positively associate the decrease in on-school incidences to another policy, then this weakens the argument made.

(D) The school system spent more on anti-smoking education programs last year than it did in all previous years.
Incorrect - This ultimately holds zero weight in the success of the program. If anything this helps the argument.

(E) The amount of time students spent in anti-smoking education programs last year resulted in a reduction of in-class hours devoted to academic subjects.
Incorrect - Can it still be stated that the program was worth it despite the decrease in class time? Yes. This is an example of an answer choice that gets you to unintentionally bring in real world experience/desire.

Kudos if my analysis was helpful!