The decidua basalis of the endometrium and the chorionic villi of the fetus grow together to form the

A) placenta.
B) blastocyst.
C) amnion.
D) ectoderm.
E) morula.

Decidua Basalis

The part of the endometrium (lining of the uterus) that specifically provides the maternal portion of the placenta and undergoes significant changes during pregnancy.

Chorionic Villi

Microscopic, fingerlike projections that emerge from the outer cellular layer of the chorion, contributing to the placenta and facilitating nutrient and oxygen exchange between the mother and fetus.

Endometrium

The inner lining of the uterus that thickens during the menstrual cycle in preparation for possible implantation of an embryo.