Answer:
The correct option is D) studying how the mayfly population affects the number of trout in a stream .
Step-by-step explanation:
In general, ecology can be described as the study of the interaction of organisms with the biotic and abiotic components of an ecosystem. It is the study of the interaction of organisms with one another and with their biophysical environment. The statement mentioned in option D shows the interaction between the mayfly population and the trout population. Hence, it is the option which would directly be related to the science of ecology.