This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Normal Menstruation, Abnormal Menstruation, Menopausal Physiology and forsight of conception, Subject name: Gynaecology & Obstetrics
Resolution of corpus luteum occurs because of: 
Select and explain. 
A. Increased levels of progesterone, B. Increased levels of estrogen, C. Decreased levels of LH, D. Decreased levels of FSH
C: Decreased levels of LH
Answer: C: Decreased levels of LH 
Explanation: Continued corpus luteum function depends on continued LH production. In the absence of this stimulation, the corpus luteum will invariably regress after 12 to16 days and form scar-like corpora albicans. In the absence of pregnancy, the corpus luteum regresses, and estrogen and progesterone levels wane. If pregnancy occurs, HCG from the placenta will mimic LH action and the corpus luteum continues to secrete progesterone.