Answer:
C. gene B only
Step-by-step explanation:
Housekeeping proteins are essential for all cells throughout it human body, to maintain basic function. So, if gene B is expressed in two different organs, such as brain and liver, it suggests that B is a housekeeping protein. Examples of this kind of proteins are the ribosomal proteins, RNA polymerases, cytoeskeleton proteins, and some of the mitochondrial proteins, among others.