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
CA - 125 is a tumor marker for: 
Select and explain. 
A. Carcinoma ovary, B. Carcinoma endometrium, C. Carcinoma vagina, D. Carcinoma cervix
A: Carcinoma ovary
Answer: A: Carcinoma ovary 
Explanation: None