Answer D verse B

@Samantha-Alexis, Happy to help. (B) says, "Its climatic conditions have been severely interrupted in the past by a succession of ice ages." Although we know from lines 11-13 that temperate zones have been affected by ice ages, we also know from lines 13-15 that some temperate zones have experienced less disruption than others have from ice ages. Thus, (B)'s wording is too strong, as it's stating that this particular grassland has been strongly affected by an ice age. We can't quite make that conclusion based on what we know, so (B) is out. Hope this helps. Let us know if you have any other questions!

Can you explain why D is correct? Like where are the passages (lines) to support D? I can't figure it out. Thank you.

@Jess - not an instructor - but I think D is correct because the phenomenon being explained (greater # of species the closer you get to the equator) combined with the fact that the temperate climate zone is closer to the equator than the arctic allows you to infer D