Concept: Consider the food chain of a grassland ecosystem as shown below
Grasses – Rabbit – Fox – Lion

• The first trophic level in this food chain is occupied by producers, which are the grasses. Because it consumes grasses, the rabbit is a herbivore and the main consumer in this food chain. 
• Due to their carnivorous nature, foxes will occupy the position of secondary consumers at the top of this food chain. Lion is a tertiary consumer at the next trophic level, where lions can devour foxes. 
• In both grassland and forest habitats, lions are tertiary consumers.
• In a food chain, there are several trophic levels, and the organisms are maintained at every trophic level according to their feeding habits.

Hence, option C is the correct answer.