Ans. (A). Chimpanzees.
The humans were evolved about 5-7 million years ago, along with chimpanzees from a common homonid ancestor, known as CHLCA (chimpanzee-human last common ancestor). The humans and chimpanzees were evolved from CHLCA as two different species by speciation.
This is why, chimpanzees are closest living relatives of humans as they both are sister species as they share a most common ancestor.
Thus, the correct answer is option (A).
