This is a Determine the Function question. We need to dissect the structure of the argument in order to answer this one correctly. We can break the argument into three parts. The first part is the conclusion. The second part is an opposing point that, although admitted to be true, does not refute the conclusion. The third part is the direct evidence for the conclusion. The question asks us about the second part of the argument, so we are looking for an answer choice that says it serves as an opposing point that does not disprove the conclusion _ best stated in answer choice (B).
(A) is not true. The claim is not supported by any other claim in the argument.
(B) is true. The claim is an observation that is conceded but is argued does not disprove the conclusion.
(C) is really tempting but not true. The argument never contends that the point is a "primary" obstacle. The claim is an obstacle as it is an opposing point. But that does not mean that it’s the primary obstacle.
(D) is not a true statement. The author does not believe the statement is false.
(E) is not a true statement. The claim is an opposing, rather than supporting, point.