GMAT Sentence Correction (SC) | Re: The 32 species that make up the dolphin family are closely

Here is the explanation:

- The subject is "32 species", which is plural. The verb for the subject should be include (as "includes" is singular)
- "...include the animal known as the killer whale" is pointing to 32 species. The sentence says that there are, in total, 32 species, one of which is the killer whale

D & E are out because of sub-verb issue.

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