In human beings,after .............. month of pregnancy,the embryo's heart is formed.

The hormone relaxin,responsible for the easy birth of the baby,is secreted by . . . . . . .

Match List-$I$ with List-$II$ related to embryonic development at various months of pregnancy:

List-$I$	List-$II$
$A$. The foetus movement starts and hair appears on the head	$I$. $24$ weeks of pregnancy
$B$. The foetus develops limbs and digits	$II$. $20$ weeks of pregnancy
$C$. The foetus develops external genital organs	$III$. $8$ weeks of pregnancy
$D$. The foetus body is covered with fine hair; eyelids separate and eyelashes are formed	$IV$. $12$ weeks of pregnancy

Choose the correct answer from the options given below:

Which hormone relaxes the pubic symphysis during childbirth?

Thalidomide is a non-barbiturate sedative drug which was given to pregnant women. Its use was withdrawn in $1961$ because it resulted in phocomelia. This condition illustrates:

The hormone responsible for the implantation of the embryo in the uterus and the formation of the placenta is: