Easy
Find out the organism which cannot be included in the third trophic level.
Explanation
Explanation
In a typical food chain (grass -> rabbit -> frog/snake -> eagle), the rabbit is a primary consumer (herbivore) at the second trophic level, not the third; frogs, tigers, and eagles are typically secondary/tertiary consumers occupying the third level.
PRO TIP
Re-check your working by substituting the answer back into the original question.