The genes for miniature wings (m) and garnet eyes (g) are approximately 8 map units apart on chromosome 1 in Drosophila. Phenotypically wild-type females (m + g / mg +) were mated to miniature-winged males with garnet eyes.
Which of the following phenotypic classes reflect offspring that were generated as a result of a crossover event?
1. garnet eyes
2. wild type
3 .miniature wings
4 .miniature wings, garnet eyes

Answer is option " 2 & 4"

Explanation:

Two types of posterity can be created subsequent to mating: parental and recombinant. Recombinants are created because of the traverse of non-sister chromatids at the hour of gamete arrangement. Here, mating happens between m+g/mg+ female and mg/mg male so the posterity would be separated as follows:  m+g/mg : Parental  mg+/mg : Parental  m+g+/mg : Recombinant  mg/mg : Recombinant  m+g+/mg (wild sort) and mg/mg (smaller than usual wings, garnet eyes) are the recombinants thus they were created because of the hybrid occasion.Hence,the right answer is option 2 & 4 "wild type and miniature wings,garnet eyes"