The minimum number of barriers present between foetal and maternal blood is present in which type of placenta?

The term blastocyst is applied to the blastula of which one of the following

Following the diagram of an ovum surrounded by few sperms :

Which of the following option is correct for the labelled parts $A, B$ and $C$?

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

Which of the following is a set of male accessory ducts?

Saheli is a

The eutherian placenta is derived from or In mammals placenta is formed by