we ar evaluating whether lowered minimum wage will reduce unemployment rate
(C) is hinting at alternate possibility of lowering it, albeit, not necessarily via lowering minimum wage
because let's say there is a change in unemployment rate with minimum wage staying stable, what does this change reflect?
did the rate go up or down?
and does it tell us if we actually lower the wage, we will get reduced unemployment rate?
No, it does not answer that
let's say there is no change in the rate if the minimum wage stays stable
but does it tell us whether lowering minimum wage will guarantee lowered unemployment rate
No, it again is silent on this aspect
Overall, this option addresses alternate ways to treat the issue given rather than assessing the viability of the solution given to treat the issue
Abhi077
OFFICIAL EXPLANATION
As always, the first thing to do is be clear on what the question is asking us, which, in this case, is to determine which information would be the most useful in assessing the advisor's argument (which is that lowering the minimum wage will lower the unemployment rate, based on evidence from other cities). We aren't trying to determine whether the advisor's argument is good, only what is the best thing to know when evaluating her argument.
Whatever valuable information the question in (A) might give us is already in the passage, whether or not the minimum wage was lowered via a "successful lobb[y]." Where most of Thomaston's residents work (and whether or not they work full time) does not clearly relate to minimum wages and unemployment rates; choice (B) isn't the best answer. Because we already have information about the effects of lowering the minimum wage in nearby cities, the information we could get from asking (C) about normal fluctuation would be valuable; this may be our answer. Though clearly tied to the topic of this passage, (D) isn't relevant to assessing the argument itself; it asks a question about the social effects of lowering the minimum wage, not whether doing so will affect the unemployment rate at all. Choice (E) is not directly relevant to what's important here, which is the unemployment rate.
Choice C is our answer