Thanks for the question! So the problem with (E) is that these lines don't introduce additional support for the dating of the LHB; in fact, talking about dating the LHB isn't even part of this paragraph. It's already stated as dated 4 billion years ago, and this part isn't presented as the reason why that dating exists.
(D) is correct because in this paragraph, the author is talking about this vigorous debate and showing why it's relevant/important, and this is what (D) points out. This is introduced as a fact that shows why studying the LHB is interesting. Oftentimes, authors will talk in the beginning of a passage in some way about why readers should care about the information in that passage, so it makes sense here, and is definitely the best out of all the answer choices. Hope this helps! Feel free to ask any further questions that you might have.
