What is a food chain ?

A food chain shows the sequence of how organisms obtain their energy.

A food chain usually starts with a plant and ends with an animal. To complete the cycle, decomposers come in to clean up the waste and return nutrients to the soil.

Simply stated that food chain represents the series of events in which food and energy are transferred from one organism to another in an ecosystem.

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

nucleus

would be most reasonable answer tbh