Answer:
A. division of the nucleus
Explanation:
Mitosis is a biological process that the cells of all organisms go through in order to replicate and reproduce. It is part of the cell cycle, which is made up of G1, S, G2, and M (mitosis). In G1, the cell is growing; in S, the DNA of the cell is synthesized, or replicated, so we know choice C is wrong; in G2, the cell is being prepared for mitosis; and finally, in M, the cell actually undergoes cell division.
So, we are looking for an answer choice that involves division: either A or D.
At the end of mitosis, there's an additional process called cytokinesis that actually divides the cytoplasm, so the answer can't be D.
Thus, the answer is A.
