This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sex Hormones, Subject name: Physiology
Secretory phase of endometrium is due to which hormone? 
Select and explain. 
A. Estrogen, B. Progesterone, C. Prolactin, D. Pregnenediol
B: Progesterone
Answer: B: Progesterone 
Explanation: Ref: Guyton, 12th edition, Page 995 and Essentials of Medical Physiology By Khurana, Page 509Explanation:PHASES OF ENDOMETRIAL CYCLEThe endometrial cycle of 28 days can be divided into three phases:o Menstrual Phase (1-5 days)o Proliferative Phase (6-14 days)o Secretory Phase (15-28 days).(See table on the next page)