GMAT Sentence Correction (SC) | Re: While the Eastern Whip-poor-will a nocturnal bird that feeds

While the Eastern Whip-poor-will -–a nocturnal bird that feeds mostly in the very early morning–- and the Common Nighthawk –-a nocturnal bird from the same family that, despite its name, feeds mostly during the morning and evening–- appear equal in size when sitting on a branch or in a nest; in the air, the Common Nighthawk appears much larger because of its greater wingspan.

Note the structure of the sentence:

While E and C appear equal in size
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