The sac that surrounds the fetus and usually ruptures just before childbirth is the

A) gastrula.
B) allantois.
C) yolk sac.
D) amnion.
E) archenteron.

Fetus

A developing mammal or human from the end of the embryonic stage, recognizably human in form, until birth.

Amnion

A thin membrane forming a closed sac around the embryo in amniotes, containing the amniotic fluid, which provides a protective environment.

Gastrula

An early stage in embryonic development that follows the blastula, characterized by the formation of germ layers.