Explanation: The author makes two assertions about Locke: that his ideas were not original and that his books were not very good. On the basis of these assertions, the author concludes that Locke's reputation as an intellectual giant is undeserved. Choice (C) accurately summarizes this conclusion. Choice (A) focuses on a subsidiary point, not the main idea; moreover, it makes an assumption unsupported by the passage namely, that Locke did not acknowledge the sources of his ideas. Choice (B) is wrong because although the passage clearly indicates that the author is "re-evaluating" Locke's work, it does not suggest that "current historians" in general are doing so. Similarly, (D) implies that the author recommends that other historians re-examine Locke. Since no recommendation exists in the argument, Choice (C) is the only option.
(D) is tricky because it is a good answer, BUT IT IS NOT THE BEST ANSWER.