Question

the protects our body from harm and helps regulate body temperature. hair immune system skin

Explanation:

The skin is the body's first - line defense against harm and helps regulate body temperature through processes like sweating and vasoconstriction/dilation. Hair has some minor protective and insulating roles but not as significant as skin. The immune system defends against pathogens but doesn't directly regulate body temperature in the same way as skin.

Answer:

skin