Assertion (A): Herbivores are referred to as primary consumers.
Reason (R): They obtain their food directly from plants.

Both A and R are true and R is the correct explanation of A.

The correct answer is Option (1) -Both A and R are true and R is the correct explanation of A.

In an ecosystem, herbivores are considered primary or first-order consumers because they feed directly on producers, which are plants. Since plants make their own food through photosynthesis, they represent the first trophic level. Herbivores, by consuming these plants, occupy the next level in the food chain, making them the first order or primary consumers.

The reason is that herbivores directly depend on plants for energy and nutrients, supporting their role as the immediate consumers of the producers.