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: Pharmacology
People with high risk for development of breast cancer should be treated by prophylactic administration of : 
Select and explain. 
A. Tamoxifen, B. Aminoglutethimide, C. Diethylstilbestrol, D. Flutamide
A: Tamoxifen
Answer: A: Tamoxifen 
Explanation: None