And you could explain why A series of chromosomal mutations

And you could explain why?

A series of chromosomal mutations in Drosophila were used to map the javelin mutation that affects bristle shape and henna that effects eye pigmentation. Both javelin and henna are recessive and they map to regions 65 of Drosophila polytene chromosomes. (A diagram of the chromosome banding pattern for region 65 is shown below.) The chromosomal breakpoints for 4 rearrangements are indicated on the table below. Flies with a chromosome containing one of these four rearrangements (deletions or inversions) were mated to flies homozygous for both javelin and henna). The phenotypes of the F1 are shown below: Where is the most likely location of the henna gene? between region 65 A2-3 and region 65 D2-3 between region 65 C2-3 and region 65 E4-F1 between region 65 A2-3 and region 65 E4-F1 between region 65 C2-3 and region 65 D2-3 at 65A6

Solution

Option E is the right answer. As when compared to the F1 phenotype it can be seen that it\'s inversion A does not gives henna phenotype thus it\'s inversion would have altered the gene order which results in the absence of henna phenotype.