In a human foetus,the limbs and digits develop after:

All extra-embryonic membranes:

In indeterminate cleavage,the fate of blastomeres is fixed at which of the following stages?

During pregnancy,the fetus receives some antibodies from its mother through the .............. .

Find the correct statements :
$A.$ In human pregnancy,the major organ systems are formed at the end of $12$ weeks.
$B.$ In human pregnancy the major organ systems are formed at the end of $8$ weeks.
$C.$ In human pregnancy heart is formed after one month of gestation.
$D.$ In human pregnancy,limbs and digits develop by the end of second month.
$E.$ In human pregnancy the appearance of hair is usually observed in the fifth month.
Choose the correct answer from the options given below.

What is the gestation period of an elephant?