GMAT Sentence Correction (SC) | Re: Nineteenth-century authors often included encyclopedic information in

First: The pronoun "it" is ambiguous. There are more than one possible antecedents.

Second: Even if you take "chapter" to be the antecedent for "it", the part "as it (the chapter) is" is unnecessary. This part would be justified, if a scenario of modifying the chapter were relevant.

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