GMAT Sentence Correction (SC) | Re: Covering 71 percent of Earth’s surface, the oceans play an essential

Hi guys I'm new here, anyway, I was looking for an answer here since I did not find the OA's very clear. I think the point here is that most of the answers are grammatically correct, so we gotta look at the meaning of them. The oceans play an essential role because they moderate etc, so answer A is the only one which gives that meaning. Hope I've been clear

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