Which of the following represent the nutrient contents of a water body at…

Concept — In limnology, the trophic status of a standing water body is its classification by the concentration of plant nutrients it carries, chiefly nitrogen and phosphorus, together with the biological productivity that nutrient load sustains. This is a single axis running from nutrient-poor water to nutrient-rich water. A separate family of "-trophic" words classifies living organisms by the source from which they obtain energy; those words describe the organism, not the water it lives in.

Application — Sorting the five listed terms onto those two axes:

1. Phototrophic — a mode of nutrition of an organism: energy is captured from light. Axis: energy source of an organism.

2. Eutrophic — a water body carrying a high concentration of dissolved nitrogen and phosphorus; such water supports dense algal growth and loses dissolved oxygen in its deeper layers. Axis: nutrient content of water.

3. Mesotrophic — a water body carrying an intermediate concentration of those same nutrients, lying between the nutrient-poor and nutrient-rich extremes. Axis: nutrient content of water.

4. Chemotrophic — a mode of nutrition of an organism: energy is released by oxidising chemical compounds. Axis: energy source of an organism.

5. Oligotrophic — a water body carrying a low concentration of those nutrients; such lakes are typically clear, deep and well oxygenated. Axis: nutrient content of water.

Cross-check — Reading the three water-body terms together shows that they are graded levels of one and the same quantity, while the other two sit on a different axis altogether:

Result — The three terms that name the nutrient content of a water body at different levels are Eutrophic, Mesotrophic and Oligotrophic, that is, the set "(B), (C) and (E) Only".