The lava released by a volcanic eruption separates two populations of a species of monkey. What does this represent?

A biological isolation

B geographical isolation

C temporal isolation

D anatomical isolation

on E2020 it would actually be B) geographical isolation, not A because A is biological isolation.

The right answer here is A) geographical isolation. Geographical isolation occurs when two different groups of flora or fauna that lie within the same species, are separated due to a geographical barrier - in this case, lava from a volcanic eruption.