How does current theory explain the origin of a nucleus in eukaryotic cells? Please choose the correct answer from the following choices, and then select the submit answer button.

a. A prokaryotic cell was engulfed by another cell and became specialized in DNA replication.
b. None of the other answer options is correct.
c. A prokaryotic cell was engulfed by another cell and became specialized in DNA transcription.
d. While there are some competing theories on the origin of the nucleus, neither theory discussed in the text really explains the origin of the nucleus.
e. A prokaryotic cell was engulfed by another cell and became specialized in translation.

d. While there are some competing theories on the origin of the nucleus, neither theory discussed in the text really explains the origin of the nucleus.

Explanation:

The nucleus is found in eukaryotes in which the genetic material is enclosed. Some scientists say that the nucleus is evolved from mycoplasma which is a prokaryote who was engulfed by an amoeboid cell.

Some say that the nucleus is originated from archaea which were phagocytosed by bacteria. So there are some competing theories that tell about the origin of the nucleus but do not have proper evidence to explain the origin of the nucleus. So the correct answer is d.