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: Pathology
Increased susceptibility to breast cancer is likely to be associated with a mutation in the following gene: 
Select and explain. 
A. p53, B. BRCA-1, C. Retinoblastoma (Rb), D. H-Ras
A: p53
Answer: A: p53 
Explanation: . p53