Herbivores depends on the plants.
ex:- rabbit eats grass
carnivores depends on herbivores that means it indirectly depends on plants.
ex:-Tiger eats rabbit
omnivores depends on herbivores and carnivores that means it also depends on plants for their food.
ex:- human consumes both veg and non veg.
By this we can say that all animals whether herbivores, carnivores or omnivores depends on plants for their food.