68. The menstrual cycle can be divided into four phases: ① Follicular, ② Ovulation, ③ Luteal, and ④ Menstrual. During these phases, the following endocrine changes occur: a. High estrogen and progesterone; low FSH and LH, b. Low estrogen and progesterone, c. LH surge, d. Increasing estrogen; low LH and low progesterone. Please match the correct endocrine change with each phase of the menstrual cycle. (A) ①d, ②a, ③c, ④b (B)①a, ②d, ③b, ④c (C) ①d, ②c, ③a, ④b (D) ①a, ②b, ③d, ④c