PT59 S2 Q22

babybenny

The first section of the PT59's logical reasoning is quite killing me.
Anyway, I was stuck between B and C and then chose C. But the answer is A.

I thought B or C can block another possibility which can weaken the argument and enhance the argument that nutritious breakfasts can the only reason to increase productivity of Plant A.
So I still have no idea why B or C can't be an answer and why A is correct.

Can someone explain me A, B and C?
Thanks in advance!

nye8870

Ac(A) is right because it affirms a necessary condition for the conclusion to hold up. What if workers from plant B were eating their nutritious breakfast at home? Then the study proves nothing (plant B did not increase productivity – even WITH a nutritious breakfast).
Ac(B) was tricky for me too. But it doesn’t strengthen because even if plant workers started at different times (let’s say some 6 a.m. / others 9 a.m.), the study still revolves around the nutritious breakfast. The stim states (and we must believe it) that Plant A workers got their nutritious breakfast. The real problem still remains, which is knowing or not knowing whether Plant B workers ate a nutritious breakfast (which brings us back to correct ac(A).
Ac(C) can be eliminated because the stim talks about an increase for Plant A. Maybe Plant A was always more productive than Pant B. They still became even more productive. Or maybe they were less productive, then became more. Or maybe they started off the same. In the end it just doesn’t matter.