What is the name for the protective structure that forms around the embryo

Amniotic cavity is the term used for the sac which protects an embryo from internal and external pressures. It contains the amniotic fluid which serves as the cushion for guarding the developing embryo and the system to which it is being fed on. It is a crucial part of pregnancy to be able to take tests in diagnosing the fetus for possible defects and abnormalities and one of the methods used is the amniocentesis wherein samples of the amniotic fluid are sampled.

The answer is b) gene