The chemical substance found in the surface layer of cytoplasm of spermatozoa is

Which part of the human sperm enters the ovum during fertilization?

Where does the cleavage of the zygote begin?

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 $C$?
$A$ $\quad$ $B$ $\quad$ $C$

Sperm enters from which part of the egg?

Fertilisation in humans is practically feasible only if