Step-by-step explanation:
Denoting:
Long wing gene = L
Vestigial wing gene = v
First up think of the gametes, one is hybrid so that means they have a mix of the genes so it would be (Lv) and the other is pure vestigial so it would be (vv)
**it can also be noticed that vestigial wing gene would be the recessive gene as it was only expressed on the pure strain and not on the hybrid, also meaning that the gene for long wings are dominant
Ok so like what I did in the picture, from the random fertilization, any possibilities you can see it's like 50 to 50 for having long wings to having pure vestigial wings
And in second punnet square to determine gender, it can be deduced that the possibility of getting a boy is 50% and getting a girl Is 50%
it's all in a 2:2 ratio
so basically the chances for expecting any gene on any gender were equal thus the possibilities for either long winged female or male, vestigial winged female or male
those are 4 different possibilities occurring out of 320 offspring.
simply divide 320 by 4 which = 80
this means that the actual offspring gene probability would be somewhat equal for both male and female and each around 80 hence why option D was the answer.
Hope this helped, if not please let me know and I'll explain further :)