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
Cryptomenorrhea, occurs due to: 
Select and explain. 
A. Imperforate hymen, B. Asherman's syndrome, C. Mullerian agenesis, D. All
A: Imperforate hymen
Answer: A: Imperforate hymen 
Explanation: None