Concept:The mammalian skin is involved in temperature regulation, sensation, and excretion, but it is not adapted for gaseous exchange.
Explanation:The skin helps regulate body temperature by producing sweat and by changing blood flow near the skin surface.
It receives external stimuli through sensory receptors that detect touch, pressure, heat, cold, and pain.
It performs excretion by releasing sweat, which contains water, salts, and small amounts of urea.
However, the skin of mammals is thick, dry, and largely covered with hair or keratin.
These features make the skin unsuitable for the exchange of oxygen and carbon dioxide.
In mammals, gaseous exchange is carried out mainly by the lungs, not the skin.
Answer:D. Gaseous exchange