How Can a Mutation in a Tumor Suppressor Behave as a Recessive

Multiple Choice

How can a mutation in a tumor suppressor behave as a recessive allele at the cellular level but appear as a dominant allele in pedigree analysis?

A) At the cellular level only one allele needs to be mutated for an en effect while in a pedigree the cancer may be vertically inherited.
B) At the cellular level both alleles need to be mutated for an en effect while in a pedigree the cancer may be vertically inherited.
C) At the cellular level one allele needs to be mutated for an en effect while in a pedigree the cancer may be horizontally inherited.
D) At the cellular level both alleles need to be mutated for an en effect while in a pedigree the cancer may be horizontally inherited.