Which the following Is an example of epistasis?
a. A chicken with a dominant allele at the R gene has a rose comb, and a chicken with a dominant alleles at the P gene has a pea comb. However, a chicken with dominant alleles at both R and P genes has a walnut comb
b. A person with two copies of the lA allele at the ABO gene has blood type A. and a person with two copies of the lB allele at the ABO gene has blood type B However, a person with the genotype lAIB has the blood type AB
c. A cat with two dominant alleles at the H gene has short hair, and a cat with two recessive alleles at the H gene has long hair However, a cat with a dominant allele and a recessive allele at the H gene has short hair
d. A fly with a dominant allele at the S gene has short body hairs and a fly with a dominant Q allele at the W gene has white eyes However a fly with dominant alleles at both the S gene and the W gene has short body hairs and white eyes