The animals that feed on herbivores like insects, birds & mammals in…

The correct answer is Option (4) → primary carnivores

In a grazing food chain, the herbivores (primary consumers) eat the plants. The question asks about the animals that eat these herbivores.

Option (4) primary carnivores — Correct. In a terrestrial ecosystem, herbivores such as insects are eaten by animals like birds and mammals. Animals that feed on herbivores are called primary carnivores (secondary consumers).

NCERT Extract:
Energy Flow – “… All animals depend on plants (directly or indirectly) for their food needs. They are hence called consumers and also heterotrophs. If they feed on the producers, the plants, they are called primary consumers, and if the animals eat other animals which in turn eat the plants (or their produce) they are called secondary consumers. Likewise, you could have tertiary consumers too. Obviously the primary consumers will be herbivores. Some common herbivores are insects, birds and mammals in terrestrial ecosystem and molluscs in aquatic ecosystem. The consumers that feed on these herbivores are carnivores, or more correctly primary carnivores (though secondary consumers). Those animals that depend on the primary carnivores for food are labelled secondary carnivores.”