A grown tiger began its life as a single fertilized egg. Which explains why a tiger
looks so much different as an adult than it did as a single fertilized egg.
All the genes are expressed.
Different genes are expressed at different times
Different cells have different genes.
As a tiger grows his genes change.

As a tiger grows his genes change

Explanation:

Development from a fertilized egg to a mature organism depends on the expression of different genes at different times. In addition, gene expression can occur in different parts of the body at different times during development. As the fertilized egg begins to divide, different genes are either turned on or off. The activation of specific genes is the most important step in cell differentiation. As the tiger grows and develops, different genes are either turned on or off in the tiger’s various cells. This regulation is a key part of development and differentiation.  

i would go with b

cytokinesis occurs after telophase so that eliminates d

and the entire reason for cytokinesis is for cellular reproduction