Explanation

Creating a filter: supposing that we can't find a defect in the original sentence, we can head to the answer choices.

Finding objective defects: choices (D) and (E) begin in a more succinct manner than (A) and (B), and they are equally clear. Choices (D) and (E) also allow us to avoid using "that were" twice in the sentence, which was creating awkwardness. So (A) and (B) are out. Answer choice (C) uses the more elaborate "having been discovered" without need. So (C) is out and we focus on (D) and (E). There are number of differences between them. One difference will do the trick if we are fully confident in it. "New research" indicates that something has happened recently, and for that "have yielded" in (E) is accurate. "Yields" would imply what we are talking about is generally the case, contrary to what's implied by the phrase "new research." The correct answer is (E).