Scientist have discovered a new pathogen named Virus X. This infection causes its victims to suffer from severe diarrhea and is spreading quickly across major cities around the world. During their investigation, these researchers tracked the virus back to a population of pigs in Asia. These animals were not affected by the disease themselves but large numbers of the virus were found in their feces. In particular, when visiting one farm, scientists observed workers routinely going from taking care of the pigs to picking fruits and vegetables without washing their hands. For this pathogen, the pig population would best be described as a..
vector
agent
reservoir
host

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.