Apart from endocrine function,what are the other functions of the placenta?

$hCG$ is secreted by . . . . . . .

Which organ does not participate in fetal circulation?

Match the following with respect to stages of embryonic development in human.

Column $I$	Column $II$
$a$. Fully formed morula	$i$. By end of $7^{\text{th}}$ day after fertilization
$b$. Fully formed blastocyst	$ii$. $15$ days after fertilization
$c$. Completion of implantation process	$iii$. By end of $4^{\text{th}}$ day after fertilization
$d$. Fully formed gastrula	$iv$. By end of $10^{\text{th}}$ day after fertilization

Choose the correct option-

$A$: If fertilization occurs,the corpus luteum is rescued from regression by human chorionic gonadotropin $(hCG)$,which is produced by the placenta.
$R$: In the first trimester,the corpus luteum,stimulated by $hCG$,is responsible for the production of progesterone.

The development of the zygote takes place inside the female body.