If your choices are the following (see attachment), then the answer is E gene.
It is stated that hypostatic gene<span> is one whose phenotype is altered by the expression of an allele at a separate locus, in an epistasis event. So the allele altering the espistatis event is the E gene.</span>
It is stated that hypostatic gene<span> is one whose phenotype is altered by the expression of an allele at a separate locus, in an epistasis event. So the allele altering the espistatis event is the E gene.</span>