The blood-testis barrier:

consists of tight junctions between interstitial (Leydig) cells.

is the basement membrane of the seminiferous tubules.

protects sperm antigens from exposure to the cells of the immune system.

all of these choices

R / Protects sperm antigens from exposure to the cells of the immune system.

Explanation:

In mammals there is a barrier (blood-testis barrier) within the seminiferous tubes formed by tight junctions between Sertoli cells that separates spermatogonias from primary spermatocytes. This barrier separates the seminiferous tube into two compartments, the basal and the adluminal. The basal compartment between the basement membrane and the tight junctions can be accessed by elements of the plasma and immune cells, while the second compartment is not.