Study the given diagram :
A is an embryonic stage that gets transformed into B, which in turn gets implanted in the endometrium in human females.
(a) Identify A, B and its parts C and D.
(b) State the fate of C and D in the course of embryonic development in humans.
a)
b) Stem cells form embryo and Trophoblast helps in attachment of the embryo to the endometrium as it forms the placenta.