Sometimes the separation of twins is incomplete and they are born attached and remain so even after birth. Such twins are known as:

Which of the following groups of hormones are produced in women only during pregnancy?

Select the correct option describing gonadotropin activity in a normal pregnant female.

$A$: Blastocyst undergoes gastrulation to produce the three germinal layers.
$R$: This involves cell movements (morphogenetic movement) that eventually help to attain new shape and morphology of embryo.

The villi which are formed by the allantochorion to form an intimate connection with the uterine endometrium function as:

$A$: The first sign of a growing foetus may be noticed by listening to the heart sound through the stethoscope.
$R$: By the end of the second month of pregnancy,the foetus develops limbs and digits.