Which feature distinguishes a morula from a blastula?

What is seen in the zygote during embryogenesis?

Match the following columns regarding human embryonic development:

Column-$I$ (Time of gestation)	Column-$II$ (Changes in embryo)
$P$. After one month	$I$. Major organ systems are formed
$Q$. End of second month	$II$. Formation of heart
$R$. End of three months	$III$. Development of limbs and digits
$S$. During fifth month	$IV$. Movement of fetus and hair on head

$A$: Placenta is connected to the embryo through an umbilical cord which helps in the transport of substances to and from the embryo.
$R$: Placenta acts as an endocrine tissue.

The process of cell differentiation begins and ends in which of the following stages?

The presence of $HCG$ in the urine of a woman indicates what?