In Drosophila,assume That the Gene for Scute Bristles S)is Located

Multiple Choice

In Drosophila,assume that the gene for scute bristles s) is located at map position 0.0 and that the gene for ruby eyes r) is at position 15.0.Both genes are located on the X chromosome and are recessive to their wild-type alleles.A cross is made between scute-bristled females and ruby-eyed males.Phenotypically wild-type F₁ females were then mated to homozygous double mutant males,and 1000 offspring were produced.Give the frequency of scute expected.

A) 360
B) 500
C) 75
D) 425
E) 250