Chromosome content of human cells

Attached picture question is:

1. In humans, what process must have occurred to obtain the cells at U?

a) Meiosis
b) Mitosis
c) Fertilization
d) Differentiation

2. In humans, what process occurs between U and V?

a) Fertilization
b) Differentiation
c) Meiosis
d) Mitosis

3. In humans, what process must occur before cell V forms cells W and X?

a) Recombination
b) Mitosis
c) Meiosis
d) Nondisjunction

4. In humans, cells Y and Z represent individual cells that

a) will become a 4n cell
b) are two Easter eggs
c) could develop into identical twins
d) will no longer divide

Please help and thank you