The sebaceous glands are simple alveolar glands that secrete a substance known as sebum. The secretion of sebum is stimulated ________. The sebaceous glands are simple alveolar glands that secrete a substance known as sebum. The secretion of sebum is stimulated ________.
a. by high temperatures as a protective coating
b. when one is swimming
c. when the air temperature drops
d. by hormones, especially androgens