The answer for this question is letter C. It is true that sperm and eggs have half the chromosomes as other cells. The sperm and/or the egg cell each only has 23 chromosomes, half of the original number, so that when they join to form a zygote when fertilization occurs, the zygote will have a total of 46 chromosomes, like every cell in a human does.
The others cannot be the right answer for the following reasons:
A - The complexity of an organism dos not depend on the number of chromosomes.
B - Nucleus is the only place where you can find chromosomes.
D - DNA and other proteins makes up the chromosomes.