GMAT Sentence Correction (SC) | Re: Starfish, with anywhere from five to eight arms, have a

Starfish, with anywhere from five to eight arms, have a strong regenerative ability, and ifone arm is lost it quickly replaces it, sometimes by the animal overcompensating and growing an extra one or two.

A one arm is lost it quickly replaces it, sometimes by the animal overcompensating and -"it quickly replaced it" very vague and unclear
B one arm is lost it is quickly replaced, with the animal sometimes overcompensating and - CORRECT "it" clearly refers to the "arm"
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