The correct answer is Red. Explanation & Key Takeaways: • Drosophila is also known as the fruit fly. • It is one of the model organisms in genetics and developmental biology. • The eye colour gene is present on X-chromosome. • When red eye male mates with white eye female, then all females have red eyes, and sons have white eyes. • It shows sex-linked inheritance. • White eye colour is recessive. • Red eye colour is dominant. • Rr are alleles of colour coding genes. • R codes for red colour. • r codes for white colour. • Here is the genetic cross:- +---------+------+------+ | Gametes | Xr | Xr | +---------+------+------+ | XR | XrXR | XrXR | | Y | XrY | XrY | +---------+------+------+ • As we can see from the above punnet square. • The XrXR results in red colour. • XrY male is white in colour. • Out of 4 children, 2 are red-eyed and 2 are white eyes. • All the females have red eyes. • The genotype of females is XrXR and XrXR respectively. • A mixture of white and red does not occur because its shows dominant recessive interaction. • A mixture of red and blue will not occur as the alleles are red and white. Related Concepts: • Drosophila is also used for determining linkage. • Two or three-point tests crossing over and determining the functioning of the genes are done using drosophila.