Question

The term oligotrophic refers to

• A. Higher nutrients in the water
• B. High aquatic productivity
• C. Algal blooms
• D. Low nutrients and low productivity

Hint:

Oligotrophic = nutrient-poor and low productivity, typical of clear mountain lakes.

Answer 1

The Correct Option is D

Oligotrophic water bodies are characterized by low concentrations of nutrients, especially phosphorus and nitrogen, resulting in low primary productivity and clear water.

Answer 2

Alternate approach — Trophic spectrum comparison:
Water bodies are classified along a nutrient gradient: oligotrophic (low nutrients), mesotrophic (moderate), and eutrophic (high nutrients, often with algal blooms). Checking each option against this spectrum, 'higher nutrients' and 'high productivity' describe eutrophic water, and 'algal blooms' is a symptom of eutrophication, not oligotrophy. By elimination, the only description matching the oligotrophic end of the gradient is low nutrients coupled with low productivity, since clear, nutrient-poor lakes cannot support dense algal or plant growth.
This confirms option Low nutrients and low productivity as correct.