In mitosis of a single cell, the nucleus
a) enlarges
b) splits into two.
c) splits into four.
d) loses half of its chromosomes.

B) splits into two. During the cell cycle the cell's nucleus will make a copy of it's DNA in a stage called the S phase. If a cell starts with 12 chromosomes it will have 24 by the end of the S phase. Next the cell moves through G2 to prepare for cell division and finally mitosis which is the division of the cell's nucleus. Each nucleus will receive a complete set of the original's cell's DNA.

I’m not exactly sure what your trying to ask, but if it’s how an organelle is similar to a body system or a part a nucleus is like a in function. but i don’t fully understand what you’re trying to ask