Final answer:
In a balanced aquatic ecosystem, plankton would have the greatest population, serving as the primary producers at the base of the food web. Therefore, the correct answer is D. Plankton.
Step-by-step explanation:
In a balanced aquatic ecosystem, the greatest population is typically composed of organisms at the base of the food web, which in this case would be plankton. the correct answer is D.
Plankton includes both phytoplankton, which are photosynthetic organisms, and zooplankton, which are tiny animals that feed on phytoplankton. Phytoplankton is crucial for the ecosystem as they provide the primary source of energy that supports the food web.
An element that could boost the growth of phytoplankton if added in large amounts to the ocean is nutrients such as nitrogen and phosphorus. These are essential nutrients that phytoplankton require for growth and reproduction.
The correct answer to the question is D. Plankton, due to their role at the base of the food web and their ability to reproduce rapidly in the presence of adequate nutrients.