I’m fruit flies, the gene for red eyes (r) is dominant and the gene for sepia eyes (r) is recessive. if a red eyed heterozygous fly (rr) mates with a sepia eyed homozygous fly (rr) what are the possible genotypes for their offspring? a) rr only b) rr, rr, and rr c) rr and rr d) rr and rr

The answer is Rr and rr.

We know:
r - recessive allele
R - dominant allele
RR - dominant homozygote with red eyes
Rr - heterozygote with red eyes (since one dominant allele R can mask recessive allele r)
rr - recessive homozygote with sepia eyes

Heterozygote Rr can give to the offspring either dominant allele R or recessive allele r. Recessive homozygote rr can give to the offspring only recessive allele r (take a look at the uploaded image of Punnett square).
After crossing the parents:
Parents:        Rr    x     rr
Offspring:  Rr    rr    Rr    rr

So:
2 out of 4 offspring will be with heterozygous with red eyes Rr: 2/4 = 0.5 = 50%
2 out of 4 offspring will be with homozygous with sepia eyes rr: 2/4 = 0.5 = 50%

C) Rr and rr will be your answer for this question