The correct answer is Option (1)- Plants

The first trophic level in an ecosystem is comprised of plants. Plants, also known as producers, are organisms capable of photosynthesis. They convert solar energy into chemical energy by capturing sunlight and using it to synthesize organic compounds, primarily through the process of photosynthesis. These organic compounds, such as carbohydrates, serve as a source of energy and nutrients for all other organisms in the ecosystem.

Herbivores, which are animals that feed exclusively on plants, occupy the second trophic level. They obtain their energy and nutrients by consuming plant material.

Carnivores, on the other hand, are typically found at higher trophic levels and feed on other animals. They are considered secondary or tertiary consumers in the food chain.

Omnivores are organisms that have a diet consisting of both plant and animal matter. They can be found at various trophic levels, depending on their specific feeding habits.

In summary, plants constitute the first trophic level in an ecosystem as primary producers, serving as the foundation of the food chain by converting solar energy into chemical energy through photosynthesis.