38. Which of the following statements about the reproductive cycles of human female is FALSE? (A) Low level of estradiol inhibits the secretion of pituitary gonadotropins. (B) High level of estradiol stimulates the secretion of pituitary gonadotropins. (C) High level of estradiol and progesterone stimulates the secretion of pituitary gonadotropins. (D) High level of LH (luteinizing hormone) stimulates ovulation. (E) High level of estradiol and progesterone stimulates the maintenance of endometrium.