Choice A

@candace, Happy to help. (A) says, "whether or not one can assume that the increase in the number of Mexican Americans born in the United States led to an increase in Mexican American political activism" This answer is quite tricky. However, the problem with this answer choice is that the author of the passage does not actually express uncertainty about whether or not one can assume that an increase in the number of Mexican Americans born in the United States led to an increase in political activity among Mexican Americans. Rather, what the author says is that since we do not possess a strong understanding of how variables (such as the rates of immigration, naturalization, bilingualism, and other variations in the ethnic consciousnesses) affect the level of political involvement of Mexican Americans, we cannot assume that an increase in the number of Mexican Americans spurred an increase in political activity (lines 52-60). In stating this, the author of the passage isn't uncertain when she says that we cannot conclude that an increase in Mexican Americans led to an increase in political activity. This is why we can get rid of (A). Does this make sense? Let us know if you have any more questions!

Yes, that makes sense. Thank you for your help.