Sentence Correction (SC) | Re: One of the earliest known birds with a beak and contour feathers, Conf

One of the earliest known birds with a beak and contour feathers, Confuciusornis sanctus,with large clawlike “thumbs” on its wings, which probably helped them to climb up to a launching position for flight.

A. with large clawlike “thumbs” on its wings, which probably helped them to
-"its" wings does not correlate to "them" -- singular w/ plural here.

B. with large clawlike “thumbs” on their wings, which probably helped it to
-same here as "A"

C.
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