The first movement of the fetus and the appearance of hair on the head are usually observed during which month of pregnancy?

Blastopore is found in

Assertion : After ovulation,the Graafian follicle transforms into corpus luteum.
Reason : The corpus luteum secretes a large amount of progesterone.

After one month of pregnancy,the embryo's $A$ is formed. By the end of the $B$ month of pregnancy,the foetus develops limbs and digits. By the end of $C$,most of the major organ systems are formed,for example,the limbs and external genital organs are well-developed. By the end of $D$,the body is covered with fine hair,eyelids separate,and eyelashes are formed. Here $A$ and $D$ refer to:

In mammals,the relaxin hormone is secreted by:

Following changes can be seen in the first trimester of pregnancy,$EXCEPT$: