Dominant epistasis ratio with A as epistatic gene 12:3:1 corresponds

dominant-epistasis-ratio-with-a-as-epistatic-gene-12-3-1-corresponds

Dominant epistasis ratio with A as epistatic gene 12:3:1 corresponds to ________________

A. A/- B/- : A/- b/b : a/a B/-

B. a/a B/- : a/a b/b : a/a b/-

C. A/A B/-: A/- B/-: a/a b/b

D. A/- -/- : a/a B/-: a/a b/b

The question was posed to me by my school teacher while I was bunking the class.

My enquiry is from Epistasis in portion Extension and Deviation from Mendelian Genetic Principles of Cytogenetics

Right option is D. A/- -/- : a/a B/-: a/a b/b

To explain I would say: In case of dominant epistasis, if there is atleast one dominant allele here A in the epistatic locus, the gene combination at B locus will not affect the phenotype. So the combination at B can be written as -/-.