15. Which of the following statements are correct?
(I)Hormones often regulate homeostasis through antagonistic functions.
(Ⅱ) Hormones of the same cherical class usually have the same function.
(Ⅲ) Hormones are secreted by specialized cells usually located in exocrine glands.
(Ⅳ)Hormones are often regulated through feedback loops.
(A) only II andⅢ
(B) only I and IV
(C) only I andⅢ
(D)only Ⅲ and IV