The following graph shows the results of an experiment in which normal men were given testosterone over a period of months (indicated by the bar from A to E). Control values of hormones were measured prior to the start of the experiment. From time B to time C, the men were also given FSH. From time D to time E, they were also given LH. Based on the information given, answer the following questions.

(a) Why did testosterone level increase beginning at point A?

(b) Why did LH and FSH levels decrease beginning at point A?

(c) Predict what happened to the men’s sperm production in the A–B interval, the B–C interval, and the D–E interval