According to genetic evidence, two main lines of descent emerged from the last universal common ancestor. One of these lines gave rise to the

a. Archaea and Eukarya.

b. Bacteria and Archaea.

c. Bacteria and Eukarya.

d. Eukarya, Bacteria, and Archaea.

The correct answer is a. Archaea and Eukarya

Explanation:

In 1990 Carl Woese divided all the organisms into three domains. These three domains are bacteria, archaea, and eukaryota. Carl Woese used 16S rRNA sequencing to differentiate the organisms into these groups.

So according to the genetic evidence, from the last universal common ancestor, two main lines are descended. As archaea were found more genetically similar to eukaryotes, therefore, one of the lines gave rise to archaea and eukarya and another line gave rise to bacteria.

As bacteria was found genetically different from the other two group so they are put separately. So the right answer is a.