In fruit flies, the gene for red eyes (R) is dominant and the gene for sepia eyes (r) is recessive. If a red-eyed homozygous fly (RR) and a red-eyed heterozygous fly (Rr) mate together, what are the possible genotypes of their offspring? (Hint: You many want to complete a Punnett square.)
A. RR and rr
B. Rr only
C. Rr and RR
D. RR, Rr, and rr