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.

the potatoes have high sugar concentrations and although these potatoes were different we could seethe effects that their sugar concentrations had in different environments. for example, the potatoes in sample a, were placed in pure water. this created a hypertonic environment and caused the potatoes to draw in water from its surroundings. we saw the opposite happen with the potatoes in sample b when placed in the sodium chloride solution. the potatoes in this case were in a hypotonic solution and therefore lost water to their surroundings.