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: Gynaecology & Obstetrics
In a case of secondary amenorrhoea who fails to get withdrawal bleeding after taking estrogen and progesterone, the fault lies at the level of : 
Select and explain. 
A. Pituitary, B. Hypothalamus, C. Ovary, D. Endometrium
D: Endometrium
Answer: D: Endometrium 
Explanation: Endometrium