When the ambient temperature is high:

A) the dermis produces less collagen, which temporarily decreases the skin's ability to retain warmth.
B) blood vessels in the dermis dilate, which increases blood flow to the skin and allows heat to dissipate.
C) sweat glands in the epidermis produce sweat, which is evaporated from the skin surface by the air.
D) constriction of the vessels in the dermis brings warm blood to the surface of the skin, where it is eliminated.

Answer: B) blood vessels in the dermis dilate, which increases blood flow to the skin and allows heat to dissipate.