Answer:
Aerobic bacteria can be used to use the available oxygen in the water to degrade the pollutants in the waste and convert it into energy it can use for its metabolic processes.
D. A struggle for existence is apparent.
If a struggle for existence is apparent, natural selection occurs because all of the weak/unfit/unadapted ones die.
They are neither, they do not have the mechanism to ingest or produce food.
