If no fertilized egg is implanted into the uterus, what happens to the corpus luteum and the levels of estrogen and progesterone?
1) The corpus luteum degenerates and the levels of estrogen and progesterone decrease.
2) The corpus luteum continues to function and the levels of estrogen and progesterone remain the same.
3) The corpus luteum regenerates and the levels of estrogen and progesterone increase.
4) The corpus luteum shrinks but the levels of estrogen and progesterone increase.