Biologists believe modern apes

a. are the ancestors of humans

b. share a common ancestor with humans

c. are descended from humans

d. are not related to humans

b. share a common ancestor with humans

Explanation:

Biologists believe that humans and modern apes like gorillas and chimpanzees shared a common ancestor called as CHLCA or Chimpanzee-human last common ancestor. CHLCA existed around 8 million years ago. The species diverged into two lines from here. One evolved into gorillas and chimpanzees and the other evolved into hominids which are considered as early human ancestors.

From CHLCA around a dozen hominid species evolved each eventually becoming extinct. Some of them are considered to be the direct ancestors of Homo sapiens.