A. I /IV
B. IV /II
C. II /III
D. II /IV
参考答案:
D
本题详细解析:
D
Choice D is correct because estrogen increases FSH receptors in the follicles which leads to an increase in estrogen secretion so it is positive feedback (II). IV is negative feedback because FSH increases estrogen which causes a decrease in FSH. Choice A is incorrect because estrogen does not increase FSH secretion. Choice B is incorrect because IV is negative feedback and II is positive feedback. Choice C is incorrect because III is not positive feedback because estrogen increases LH secretion which does not increase estrogen.
