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: Surgery
Breast cancer is epidemiologically commoner with ? 
Select and explain. 
A. Smoking, B. Nulliparity, C. Oral contraceptives, D. Multiparity
B: Nulliparity
Answer: B: Nulliparity 
Explanation: Answer (b) Nulliparity