Answer:
D) A chapter heading to summarize the text
Explanation: Reading through this, I mentally added the said features. I found B useless because it already tells us what a funerary is. We don't hear about other tribes, and it would only detract from the main excerpt, so sidebar is out. We don't need to know the number of these sculptures, unless there was test question about it, which I doubt. Which leaves D) as the most likely answer out of all of them, because it makes the most sense to add. (Hope this helps)