Why would a scientist studying
ecological footprints be called an
"ecologist"?

Because the ecological footprint is a concept that is directly linked to the ecology of the planet.

Explanation:

The Ecologist is the professional responsible for studying and researching forest, aquatic and urban ecosystems, seeking to diminish the effects of human action on them.

This professional is always studying the ecological footprints and their consequences. This is because the term "ecological footprint" refers to the growing worldwide demand for consumer goods, which puts at risk the main natural resources of the planet. Industry and consumers are often not fully aware of the level of impact this requirement can have on the environmental balance. In other words, when a business owner decides to open a shoe factory, for example, he will spend certain amounts of natural resources before the end product can be sold. This is an ecological footprint that is directly related to the work of the ecologist.

answer; i believe the correct answer is ( proteins );

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