Apoptosis can occur by change in hormone levels in the ovarian cycle.When there is no fertilization of the ovum,the endometrial cells die because:

• A. The involution of corpus luteum causes estradiol and progesterone levels to fall dramatically
• B. LH levels rise after ovulation
• C. Estradiol levels are not involved in the LH surge phenomenon
• D. Estradiol inhibits the induction of the progesterone receptor in the endometrium