Nuclear Power Plants Must Discharge the Excess Heat Generated in the Nuclear

Nuclear power plants must discharge the excess heat generated in the nuclear process to the environment.Some plants exhaust this heat to nearby water sources.There is concern that this "thermal pollution" has an adverse effect on aquatic life near the plant.Researchers at the Environmental Protection Agency (EPA) catch 100 fish from the discharge pond of a particular power plant.They track the growth rates and life span of these fish, and compare these data to the data for fish from similar streams whose temperatures are not affected by the plant's thermal effluent.The sample in this experiment is:

A) all nuclear power plants.
B) the selected nuclear power plant.
C) all fish in the discharge path.
D) the 100 fish caught by the EPA.