The correct answer is: D. Organisms linked in food chain.
A trophic level is the position of an organism in a food chain. The first trophic level is occupied by producers, which are organisms that can make their own food using sunlight. The second trophic level is occupied by consumers, which are organisms that cannot make their own food and must eat other organisms to survive. Consumers are further divided into herbivores, which eat plants, and carnivores, which eat other animals. The third trophic level is occupied by omnivores, which eat both plants and animals.
The trophic levels are important because they show how energy flows through an ecosystem. The energy that is captured by the producers is passed on to the consumers, and so on. The higher the trophic level, the less energy is available. This is because some of the energy is lost as heat at each trophic level.
The trophic levels are also important because they show how the different organisms in an ecosystem are related. The producers are at the bottom of the food chain, and they are the foundation of the ecosystem. The consumers are at the top of the food chain, and they are the most dependent on the other organisms in the ecosystem.
Here is a brief explanation of each option:
- Option A: Only plants. This is incorrect because animals are also part of the trophic levels.
- Option B: Only animals. This is incorrect because plants are also part of the trophic levels.
- Option C: Only carnivorous. This is incorrect because herbivores and omnivores are also part of the trophic levels.
- Option D: Organisms linked in food chain. This is the correct answer because the trophic levels are formed by the organisms that are linked in a food chain.