Explanation

Creating a filter: the original sentence is problematic. It's not automatically wrong to have the subject of a sentence begin with the word "that." For example, something like the following would be fine: "That they predicted sales would be strong is no surprise." We can look for a simpler construction in the answer choices, maybe one like our example.

Applying the filter: none of the answer choices quite match our expectation. Choice (B), like (A), tries to fuse two sentences together ungrammatically. Choice (C) separates the modifying clause "who predicted..." from the noun it's supposed to modify, enthusiasts. Furthermore, (C) clouds the meaning of the sentence by leaving unclear what the enthusiasts were wrong about, since the "who" clause identifies who the scientists are, not how they were incorrect. So choices (A) through (C) are out. Choice (D) is inferior to our prediction, because it uses the somewhat colloquial pronoun "it." But choice (E) is worse in expressing the redundancy that a "fact...is no surprise." So we must eliminate choice (E), and we are left with (D). The correct answer is (D).