What accompanies sloughing of the endometrium during the endometrial cycle in a normal woman?: (A) An increase in progesterone, (B) The LH "surge", (C) A decrease in both progesterone and estrogen, (D) An increase in estradiol
Answer is C. At the end of the luteal phase, the corpus luteum is resorbed and fails to produce progesterone and estradiol, making levels fall precipitously and causing the endometrium to slough.