Based on the food chain, pick the odd one out:

plants → grasshopper → frog → tiger → snake

Tiger

The above food chain tells that plants are eaten by grasshopper, grasshopper is eaten by frog, which are correct till now. Next it tells frog is eaten by tiger, which is not actually true. So, it breaks the general trend in the food chain given in the question. But it can be rectified by putting tiger after snake. So, the correct order will be:

plants → grasshopper → frog → snake → tiger

which then removes the odd point an tell us that frog is eaten by snake and snake is eaten by tiger which is true infect.