Antisterility Vitamin is

Concept: Vitamins are historically named after the specific deficiency disease or physiological function they prevent or support — for example, vitamin C is the antiscorbutic vitamin (prevents scurvy), vitamin D the antirachitic vitamin (prevents rickets), and vitamin K the antihemorrhagic vitamin (supports blood clotting).

Application: Vitamin E (tocopherol) earned the name "antisterility vitamin" from early-1920s feeding experiments (Evans and Bishop) in which rats raised on a vitamin-E-deficient diet failed to reproduce normally; supplementing the diet with wheat-germ oil, rich in vitamin E, restored normal reproduction. Vitamin E is a fat-soluble antioxidant that protects cell membranes, including reproductive tissue, from oxidative damage, which underlies this historical fertility-linked name.

Cross-check: contrasting the naming convention against the other offered vitamins confirms it points only to vitamin E:

• Vitamin B (the B-complex group, e.g. B1, B12) — water-soluble coenzymes for energy metabolism and nerve function; deficiency causes beriberi or pernicious anemia, conditions unrelated to fertility.

• Vitamin A (retinol) — required for the visual cycle and epithelial maintenance; historically called the anti-xerophthalmic vitamin because its deficiency causes night blindness.

• Vitamin K (phylloquinone) — needed for hepatic synthesis of clotting factors; historically called the antihemorrhagic vitamin because its deficiency causes bleeding disorders.

Since only vitamin E carries the historical fertility-linked designation among the options offered, the antisterility vitamin is Vitamin E.