Scientists, puzzled about the development of penicillin-resistant bacteria in patients who had not been taking penici...

Skylar February 13, 2020

@Sturnerg5, happy to help!

We know that this is an Argument Structure question because of the question stem "which one of the following most accurately characterizes the role played in the passage by...." However, this is not our typical type of Argument Structure question because, as you point out, it does not refer to an explicit part of the passage. Instead, it asks for the role played by an "unstated assumption" that the passage allows us to make.

The unstated assumption we are asked to evaluate is "that some patients who take penicillin develop bacteria with an immunity to penicillin." Again, this is not stated outright in the passage. Instead, the first sentence allows us to infer it. We are explicitly told that scientists are confused about "the development of penicillin-resistant bacteria in patients who had not been taking penicillin." The fact that scientists are puzzled by these results implies that they are abnormal, which means that at least some patients who take penicillin will develop penicillin-resistant bacteria.

Now that we see where the unstated assumption fits in, what is its function? It shows us that the phenomenon in question is not as we would expect, which sets up the scientists to do the research that is described in the rest of the passage. Answer choice (C) explains this, so it is correct.

Does that make sense? Please let us know if you have any other questions!