Both parents are homozygous for the trait. Both parents are heterozygous for the trait. The male is heterozygous and the female is homozygous recessive for the trait. The male is homozygous dominant and the female is heterozygous for the trait.
I gave my students this multiple choice question: In fruit flies, red eyes are dominant over sepia eyes. A male with red eyes is crossed with a female with sepia eyes producing first generation offspring that all had sepia eyes. What does this indicate about the flies that were crossed?

Only one answer is correct among these 4 choices:
- Both parents are homozygous for the trait.
- Both parents are heterozygous for the trait.
- The male is heterozygous and the female is homozygous recessive for the trait.
- The male is homozygous dominant and the female is heterozygous for the trait.

Could you tell me which one is correct?

The male is heterozygous and the female is homozygous recessive for the trait.