Answer:
Option A is correct.
The genotype of 100% red eyed flies will be "XRXr, XRY, XRXr, XRy"
Step-by-step explanation:
As the red color of eyes in Drosophila is dominant, so the flies having even only one R will be having red eyes colors in a phenotype. So, all the flies male or female having R will be having red eyes for sure. Option A is the correct answer.