Correct option is B
Explanation-
This is a classic case of complementation, where two mutations in different genes restore the wild-type phenotype in offspring. Therefore, the mutations affect different genes and are non-allelic.
Genetic Principle:
Complementation Test: If two recessive mutations produce a wild-type phenotype when crossed, they are in different genes → non-allelic.
In this case:
Apricot mutation affects one gene (e.g., white gene).
Sepia mutation affects another gene (e.g., brown gene).
When both functional copies are brought together in F1 → wild-type eye color is restored.
This confirms the genes are non-allelic and affect different steps in the pigment pathway.
Incorrect options-
Option a - Allelic
Allelic mutations occur at the same gene locus. If you cross two flies with different mutant alleles of the same gene, F1 offspring will still show a mutant phenotype or a partial phenotype (e.g., hypomorphic). In this case, F1 shows wild-type, which means the mutations are not allelic.
Option c - Pseudo-allelic
Pseudoalleles are closely linked genes that appear to behave like alleles of a single gene. While this seems tempting, apricot and sepia are not pseudoalleles of the same gene — they affect entirely different genes (e.g., white, scarlet, brown). Hence, the interaction here is not due to pseudoalleles, but true non-allelic complementation.
Option d- Paralogous genes
Paralogous genes are genes that evolved from a common ancestral gene through duplication, and may have similar functions. This term applies in evolutionary biology and gene family studies, not in classical genetic complementation. The concept of complementation in this question has nothing to do with paralogs.
So, the correct answer is option b - Non-allelic.
