Definition: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Input: Question: Which gene is most frequently associated with acquired mutations in breast cancer? 
 Options:  <1> p53. <2> PTEN. <3> BRCA-2. <4> BRCA-1. <5> Her2 / neu.
