"top" carnivores: 1) consume primarily herbivores.
2) rely directly on primary producers for energy.
3) consume primarily carnivores.
4) are more common than secondary consumers.
5) rely on symbiotic bacteria living in their digestive systems to digest cellulose.

3) consume primarily carnivores.

Explanation:

Carnivores are animals that consume other animals to obtain energy and nutrients, this can happen through predation or scavenging. A top carnivore or apex predator is a carnivore at the top of the food chain, this means that it doesn't have predators and it consumes secondary consumers (that are also carnivores).

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your answer is "the 1950's"