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
All of the following may predispose to Endometrial Ca, except: 
Select and explain. 
A. Un-opposed Estrogen, B. Oral contraceptive, C. Radiation, D. Tamoxifen therapy
B: Oral contraceptive
Answer: B: Oral contraceptive 
Explanation: Oral contraceptives will not predispose to Endometrial Ca. Ref: Current Obs and Gynae Diagnosis and Treatment, 9th Edition, Page 916 ; Shaw's Textbook of Gynaecology, 12th Edition, Pages 302-3