(A) tells us that native peoples from a different continent also practiced astronomy. But because we're trying to establish that these lines specifically are related to astronomy, that's not good enough. General claims about native peoples' astronomy practices don't weaken the objection about these particular lines.

(B) proposes concrete relationships to astronomy for both groups of lines, effectively weakening the objection. If the sunburst directed observers to look at particular points in the sky, and the bird represented a constellation, that undermines the claim that the two groups of lines have unrelated purposes.

There are two problems with (C). First, (C) doesn't mention the bird pattern, which means we can't undermine the objection that the patterns are unrelated. Second, (C) doesn't link the sunburst pattern to astronomy either. This again fails to weaken the objection.

Like (A), (D) explains the astronomical practices of certain native peoples, but there's no link to the Peruvian desert lines. This means (D) can't help us weaken the claim that the two groups of desert lines are unrelated to astronomy.

Without more information, when the lines were made doesn't tell us about their purpose, so (E) doesn't weaken the objection. In fact, if the gap was long enough, (E) might even strengthen the objection—lines made centuries apart might be less likely to be related.