Final answer:
Epistasis involves the interaction between non-allelic genes where one gene masks or alters the expression of another. An example can be seen in mice pigmentation, where the gene necessary for pigment production can mask the expression of the coat color gene, leading to an albino phenotype regardless of the actual coat color genetics.
Step-by-step explanation:
The correct statement that describes an example of epistasis is: b) It involves the interaction of non-allelic genes, affecting the expression of one gene by another. This phenomenon occurs when one gene (the epistatic gene) masks or interferes with the expression of another gene (the hypostatic gene). Often, the biochemical pathway involves a sequence where the product of one gene is required for the next step which is in turn controlled by another gene.
An illustration of epistasis is the coat color in mice. For instance, the agouti coat color, which is a wild-type, is dominant (AA) to solid-colored fur (aa), but it is contingent on another gene (C) necessary for making pigment. Animals with the recessive c allele will be albino because they can't produce pigment, showing that the C gene is epistatic to the A gene.