The fertilized egg divides by the process of

Observe the diagram of an ovum surrounded by a few sperms:
Which of the following options is correct for the labelled parts $A, B$ and $C$?
$A$ $\quad$ $B$ $\quad$ $C$

Meroblastic cleavage refers to one of the following types of division of eggs.

Incomplete cleavage is a type of which division?

Twins are born to a family that lives next door to you. The twins are a boy and a girl. Which of the following must be true?

Which one of the following is the most likely root cause why menstruation is not taking place in a regularly cycling human female?