Question

read the passage.
chimpanzees and humans
humans and chimpanzees descended from a common ancestor, a gorilla - like creature that lived millions of years ago. even in light of this fact, it is astonishing to learn just how similar humans and chimpanzees are when it comes to their genes. in fact, the two species dna differs by only 1.2 percent. a laboratory comparison of chimp - and human chromosomes - strands of dna each containing approximately 1,100 genes - reveals a strikingly similar pattern. perhaps surprisingly, chimpanzees are genetically closer to humans than to gorillas. admittedly, the apparently small 1.2 percent variation between chimps and humans still corresponds to forty million differences in dna base pairs. still, the tremendous genetic similarity indicates that the chimpanzee (along with the bonobo, another ape) is our closest living relative.
what is the main, or central, idea of the passage?
humans and chimpanzees descended from the same ancestor.
chimpanzees and humans have surprisingly similar dna.
chimpanzees, gorillas, and humans have significant genetic similarities.

Explanation:

The passage starts by mentioning a common - ancestor but then focuses on the genetic similarity between chimpanzees and humans, stating that their DNA differs by only 1.2 percent and highlighting the striking genetic similarity despite some differences.

Answer:

Chimpanzees and humans have surprisingly similar DNA.