Phylogenetic Studies of HIV-1 Emergence That Used Molecular Clock Estimates

Phylogenetic studies of HIV-1 emergence that used molecular clock estimates demonstrate that:

A) the disease likely emerged with the growth of major settlements in central Africa.
B) the largest peak in SIV diversification rate occurred within the last 5 million years.
C) the common ancestor of the HIV-1 virus existed in the 1980s.
D) the virus hopped from chimpanzee to human hosts four separate times.