The wild-type coat color, agouti (AA) is dominant to solid-colored fur (aa). However, a separate gene C, when present as the recessive homozygote (cc), negates any expression of pigment from the A gene and results in an albino mouse. Therefore, the genotypes AAcc, Aacc, and aacc all produce the same albino phenotype. A cross between heterozygotes for both genes (AaCc x AaCc) would generate offspring with a phenotypic ratio of 9 agouti:3 black:4 albino. Which type of gene interaction is this?
a. Complementary gene interaction.
b. Duplicate gene interaction.
c. Dominant gene interaction.
d. Recessive epistasis.
e. Dominant epistasis.
Answer: d. Recessive epistasis.
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