Explanation

Reading the question: the fund manager's argument has many error-prone features. It draws conclusions from a group of things, it deals in percentages, and it makes comparisons. We will use term matching to hunt for an error, starting with the conclusion.



Creating a filter: each half of the conclusion is connected in multiple dubious ways to the evidence. The right answer will probably involve a bad bridge from the evidence to one or to the other. For example, the evidence is saying stock funds have beat the market "on average." But that is not the same as saying that "most of our investment products" have beat the market. Most could, in fact, be failures, with one anomalous market saving the average. The second sentence doesn't help this problem. So we'll paraphrase this error as "average <> most" and use that as our filter.

Applying the filter: (D) matches our filter precisely. Choice (A) is not really an error, given the second sentence of the prompt. (B), similarly, describes something the argument doesn't do. (C) is similar to (D)--but who knows what the probability really is? It's not necessarily high. (E) is similar to (D)--but pointing out that "any one" product might have done poorly doesn't actually undermine the argument much, because it still allows for "most of our investment products" to beat the market. The correct answer is (D).