Your classmate asks your teacher why viruses are so hard to define. Her response would likely be:

"Scientists from all over the world study them and can't agree on the same definition."

"New viruses that don't fit our definitions are discovered all the time."

"Viruses are good for humans, and others are harmful."

"Some viruses are good for humans, and others are harmful."

The answer would be c, white eyes are homozygous recessive. in the early 1900s, morgan conducted several experiments with vinegar  flies (drosophila). one  sample revealed an anomaly: a  white-eyed, single male fly. he attempted to breed this fly with the typical red-eyed females. the offspring were all red-eyed. using flies from this new generation (brother-sister pairs)  produced some red-eyed and a few white-eyed flies. the white-eyed were all male. in later experiments, he was able to produce white-eyed females. this proved that white eyes are not lethal to either sex (ruling out a and b). since the percentage of white eyes to red eyes is so low, white eyes are not a dominant trait. it would be a recessive trait.