Unlike many species of migratory birds, the Arctic Tern's annual migration route covers a far greater distance than any other known animal, traversing nearly 50,000 miles.
Correct: B
The original sentence makes an illogical comparison: it compares 'the Arctic Tern's annual migration route' (a route) to 'any other known animal.' For a comparison to be logical, it must compare similar things. Option B correctly compares 'the Arctic Tern's annual migration route' to 'that of any other known animal,' where 'that' correctly refers to 'the migration route,' ensuring a parallel and logical comparison between two routes. Options A and E repeat the illogical comparison. Option D corrects the comparison by making 'the Arctic Tern' the subject, but the introductory modifier 'Unlike many species of migratory birds' correctly introduces a comparison between species, so keeping the Arctic Tern as the subject would be appropriate for that. However, the original sentence structures the comparison around the *route*, making option B the most direct and grammatically sound correction for maintaining that structure. Option C introduces an unnecessary comma and 'it traverses,' making the sentence awkward and less concise.