This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast, Subject name: Pathology
Which of the following mutations in a tumour suppressor agent by apoptosis regulation causes breast cancer? 
Select and explain. 
A. p43, B. p53, C. p73, D. p83
B: p53
Answer: B: p53 
Explanation: None