Which statement correctly describes organisms in this ecosystem? 1. Organisms in level B obtain their energy directly from the Sun. 2. Organisms in level C obtain their nutrients directly from organisms in level D. 3. Organisms in level A are herbivores. 4. Organisms in level D are heterotrophic.

Option 4, Organisms in level D are heterotrophic.

Explanation:

Generally in a energy level or trophic level system, organisms are arranged on a pyramid scale in such a way that organism lying at the level A or the base of the pyramid are producers. They obtain energy from the sun and produce food for other organisms. Organism in level B is a herbivore which feed upon the plants to gain food and energy. In level C organisms that feed upon herbivores i.e the carnivores lies. At level D lies the microorganisms that feed upon dead remains of high order animals and plants. Hence, organisms at level D are called heterotrophs.  

Thus, option 4 is correct