Phenotypically wild-type F1 female Drosophila, whose mothers had mutant light eyes (lt) and fathers had mutant straw bristles (stw), produced the following offspring when crossed to double-mutant ligh.

a) 9 lt, 3 stw, 3 lt stw, 1 wild-type
b) 9 lt stw, 3 lt, 3 stw, 1 wild-type
c) 9 wild-type, 3 lt, 3 stw, 1 lt stw
d) 9 wild-type, 3 lt stw, 3 lt, 1 stw