Which hormone relaxes the pubic symphysis during childbirth?

Match the months listed in Column $I$ with the organogenesis of the foetus in Column $II$.

Column $I$	Column $II$
$(A)$ First month	$(i)$ Separation of eyelids
$(B)$ Second month	$(ii)$ Hairs on head
$(C)$ Fifth month	$(iii)$ Heart
$(D)$ Sixth month	$(iv)$ Limbs and digits

By which time of pregnancy are the limbs and digits developed in the fetus?

Identify the stages $A$ and $B$; and what is the correct labelling of $C$ and $D$ in the process of human embryonic development?

$A$ : The morula passes through the phase of compaction,producing two major types of cells: the peripheral cells and the inner cell mass.
$R$ : The descendants of the inner cell mass become the trophoblast cells.

Human placenta is called haemochorial because . . . . . . .