Vargonia has just introduced a legal requirement that

Key to getting a CR question right is understanding the flow of the argument. If you don't really understand the argument, you will have no solid means of finding the right answer. If you really understand the argument, you will likely see exactly which answer choices is best.

Here's what the argument in this prompt boils down to.

-There is a mandated student to teacher ratio in government funded schools. This is a fact.

-When a recession occurs, more students enter government funded school. This is a fact.

There is an unstated intermediate conclusion, underlined below.

-When a recession occurs, more students enter government funded schools. So, since there are more students and there is a mandated maximum student teacher ratio, when a recession occurs, government funded schools need more teachers.

Then comes the conclusion of the argument.

"Therefore, though most employment opportunities contract in economic recessions, getting a teaching job in Vargonia's government-funded schools will not be made more difficult by a recession."

The question asks which of the answer choices would be most important in order to evaluate the argument, and probably the right answer will be something that directly affects the validity of the conclusion of the argument.

(A) This is a trap answer. What is says may seem to affect the situation, possibly giving students other schools to attend during a recession, but we already know that in a recession more students enter the free of charge government funded schools.

(B) This affects the validity of the conclusion.

The conclusion is based on the idea that more teachers are needed at the schools, because there are more students at the schools. That's the demand side of the employment situation.

However, what about the supply side? What if in a recession not only are more students entering the schools but also more people are applying for teaching jobs at the schools? If the number of applicants were to increase by a proportion greater than that by which the number of students were to, then the conclusion could be incorrect.

So knowing about the supply of applicants is key to evaluating this argument.

(C) This does not matter. If there are more students, there is a greater need for teachers, regardless of what the ratio is.

(D) You could somehow come up with a story to make this seem important for evaluating the argument. The story would have to be pretty convoluted and complex though, and really there is not any direct, obvious, logical way that the proportion of workers who hold jobs as teachers in government funded schools is key for evaluating the conclusion.

(E) Whether in the past schools operated in accordance with the current mandate does not affect the need for teachers today. This answer choice might be valid were it about current adherence to the mandated ratios during recessions, because degree of adherence the the mandated ratios affects the need for more teachers.

The correct answer is B.

What we see: a Critical Reasoning "evaluate the argument" question. We need the one fact that would best tell us whether the conclusion holds.

Step 1. Find the conclusion and the evidence.
What we see: the conclusion is that a recession will not make it harder to get a teaching job in government-funded schools. The evidence: there is a cap on students per teacher, and in a recession more children enroll in these schools.
What it means: the argument runs "more students + a class size cap = schools must hire more teachers = jobs stay easy to get."

Step 2. Spot the gap.
What we see: how hard a job is to get depends on two things: how many jobs there are, and how many people want them.
What it means: the argument only counts the jobs. It ignores the people competing for them.
What we do and why: in a recession, many people lose other jobs. If they apply to teach, competition rises even if schools hire more. So the fact we need is whether applicants rise sharply in a recession.

Step 3. Test the choices.
What we see: only one choice is about the people competing for these jobs: whether qualified applicants for teaching positions rise significantly during recessions.
What it means: if they rise sharply, a job could get harder to win even with more openings, and the conclusion fails; if they do not, the conclusion holds. That one fact decides the argument.
What we do and why: check the rest quickly. (A) free schools outside the government system shift enrollment a little, not competition. (C) see the trap below. (D) the share of all workers who teach says nothing about who applies in a recession. (E) schools that broke the limit before the rule existed tell us nothing about competition now.

The trap: (C), the current student-teacher ratio. It seems to matter whether schools are already near the cap, but even if they must hire, the job can still get harder to win when applicants pour in. And the current ratio, without the limit's value, tells us little.
Faster way: when a conclusion is about how hard something is to get, think supply and demand. The argument usually covers one side; the right choice covers the other.
Takeaway: "easier" or "harder" to get a job, a seat or a loan always depends on both the openings and the people competing for them.

Answer: B