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

Placenta acts as an endocrine tissue and produces several hormones like:
$A.$ Human chorionic gonadotropin $(hCG)$
$B.$ Human placental lactogen $(hPL)$
$C.$ Estrogens
$D.$ Progesterone

What is the average birth weight of a newborn baby (in $, kg$)?

Which of the following secretes progesterone?

The hormone responsible for the implantation of the embryo in the uterus and the formation of the placenta is:

Which structure differentiates the gastrula from the blastula?