This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Blood levels of progesterone are highest during _____. 
Select and explain. 
A. The follicular phase of the ovarian cycle, B. The luteal phase of the ovarian cycle, C. Ovulation, D. Menstruation
B: The luteal phase of the ovarian cycle
Answer: B: The luteal phase of the ovarian cycle 
Explanation: Progesterone concentration in blood is highest following the surge of LH (leuteinizing hormone) following ovulation.
During ovulation, estrogen surges due to positive feedback during the follicular phase.
During menstruation, there are sharp declines in estrogen and progesterone due to reduced secretion of LH and FSH.