The Shift from the Miocene, Which Had Greater Diversity of Ape

The shift from the Miocene, which had greater diversity of ape species and fewer monkey species, to a living assemblage with greater diversity of monkey species and fewer ape species may be the result of

A) global climate changes that resulted in cooler, wetter environments less optimal for ape species.
B) differences in ability to exploit the habitats that resulted after a change in global climate.
C) cooler climates, where it is more difficult to preserve larger ape fossils.
D) declines in ape diversity, caused by competition from hominin species.