I think the best answer would be A. since the number of prairie dogs decreased from the picture on the left to the picture on the right. Hope this helped :p
 
        
                    
             
        
        
        
Two genes, BRCA1, located on chromosome 17q21 (5,6), and BRCA2, located on 13q12-13 (7–9), have been shown to predispose to familial breast cancer.
        
             
        
        
        
C. They provide instructions for protein synthesis and determine traits.