Politician: From the time our party took office almost four years ago

This is a weaken question. With these, it's important to look as closely as possible at the premises and the conclusion. Make sure you don't change the words as they're written to fix a bad argument. Often, the arguments made in CR passages are so terrible that, in taking notes, you end up making them better. Don't do it!

Politician: From the time our party took office almost four years ago the number of people unemployed city-wide increased by less than 20 percent. The opposition party controlled city government during the four preceding years, and the number of unemployed city residents rose by over 20 percent. Thus, due to our leadership, fewer people now find themselves among the ranks of the unemployed, whatever the opposition may claim.

Conclusion: Fewer people are unemployed because of party
Premise: Our party saw unemployment increase by less than 20%, other party by more than 20%

At first glance, this may look like a typical "percent isn't the same as number" kind of question. But look closely at the conclusion. The party is saying fewer people are unemployed, when they admit that there was an INCREASE in unemployment! Just because it was less than 20% doesn't make it a decrease. In reality, the fact cited totally undermines that conclusion.

The reasoning in the politician’s argument is most vulnerable to the criticism that
(A) the claims made by the opposition are simply dismissed without being specified
Problem: This argument has nothing to do with what the opposition did or didn't do. In fact, all that stuff about opposition is a big red herring. All we care about is whether or not there are "fewer people" unemployed now than before the party took power.

(B) no evidence has been offered to show that any decline in unemployment over the past four years was uniform throughout all areas of the city
Problem: Unemployment density is immaterial; we just need the overall number.

(C) the issue of how much unemployment in the city is affected by seasonal fluctuations is ignored
Problem: This doesn't address the data we've been given, and is irrelevant.

(D) the evidence cited in support of the conclusion actually provides more support for the denial of the conclusion
Answer: Yep. If unemployment INCREASED, even by 2%, that would lead one to the conclusion that MORE people are unemployed, not fewer.

(E) the possibility has not been addressed that any increase in the number of people employed is due to programs supported by the opposition party
Problem: This is tempting, because it makes it sound like the opposition might have had some effect on a later increase in employment. However, there was no increase! There was only a decrease of "less than 20%".