The endometrium
a. is the muscle layer of the uterus
b. is thickest during the preovulatory phase.
c. is the site of embryo implantation.
d. lines the vagina.
e. is directly affected by fsh 1

The correct answer is C. Is the site of embryo implantation.

Explanation:

Uterus is composed of three tissues :

1. Perimetrium: Outer layer of uterus made up of peritoneal.                             2. Myometrium: middle layer made up of smooth muscles and                       3. Endometrium: made up of simple columnar epithelium and mucous membrane.

Endometrium plays an important role during pregnancy. During pregnancy, the production of estrogen and progesterone increases. This helps the proliferation of epithelial lining and secretory gland present in the endometrium.

Progesterone hormone plays an important part in the implantation of embryo in the endometrium layer of the uterus. Endometrial glands start secreting the nutritive fluid for the development of fetus.

Thus, the correct answer is C. Is the site of embryo implantation.