GMAT Sentence Correction (SC) | Re: Nobody knows exactly how many languages there are in the

Nobody knows exactly how many languages there are in the world, partly because of the difficulty of distinguishing between a language and the sub-languages or dialects within it, but those who have tried to count typically have found about five thousand.

1) Distinguishing between a language and sub-languages or dialects within it -> it is correct as the sub-languages or dialects are under a single language.

A. and the sub-languages or dialects within it, but those who have tried to count
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