How does current affect biodiversity in rivers and streams?

The answer is: it mixes the nutrients for plant and animal use and determines a location of organisms.

Current definitely has an effect on biodiversity. But, it does not prevent organisms from living or remaining in rivers and streams, and, thus, cause a decrease in biodiversity. On the contrary, it mixes the nutrients for the organisms and also mixes water less or more saturated with oxygen. Current also determines location of organisms, so, for example, organisms able to resist this current will live in the streams or rivers where current is strong. And vice versa - less resistant organisms will live in the parts of streams and rivers where current is not that strong.

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.