The umbilical cord in mammals contains:

The fluid filled in the blastocoel cavity of blastula is

Major features of embryonic development at various months of pregnancy are given below. Choose the correct option for the correct sequential events.
$(i)$ The first movements of the foetus
$(II)$ The foetus develops limbs and digits
$(III)$ The embryo's heart is formed
$(IV)$ The body is covered with fine hairs

The cavity of the gastrula is called

Identify $A, B, C$ and $D$ in the figure given below.

The most rapid growth of the human foetus occurs during which month?