In Addition to Loss of Heterozygosity, the Second Hit in Sporadic

In addition to loss of heterozygosity, the second hit in sporadic breast cancers with breast cancer gene 1 (BRCA1) or breast cancer gene 2 (BRCA2) mutations is often which of the following?

A) Methylation of the BRCA1 or BRCA2 promoter
B) Acetylation of the BRCA2 or BRCA2 promoter
C) Deletion of the tumor-associated transplantation antigen (TATA) box in BRCA1 or BRCA2
D) Deletion of a BRCA1 or BRCA2 enhancer
E) Nonsense mutation in BRCA2 or BRCA2