Answer:
2. The gene responsible for eye color is on the X chromosome.
Explanation:
<em>For X-linked genes, a male can either be affected or unaffected because the Y chromosome is hypothesized not to carry any gene. Females on the other hand can be a carrier, affected or unaffected because the two sex chromosomes carry genes.</em>
If eye color allele in drosophilia is represented by R, the cross between F1 red-eyed heterozygous female and red-eyed males can be illustrated below:
Red-eyed heterozygous female =
Red-eyed male =
x
Progeny:
Out of the 2 male progeny from the cross, 1 () is white-eyed while the remaining one () is red-eyed
Hence, the result shows that the gene for eye color in Drosophilia is X-linked.
Option 2 is the correct answer.