Sentence Correction (SC) | Re: In 1974 a large area of the surface of Mercury was photographed from

cubs , there is a difference in meaning, although here it's not crucial. The difference is in what is revealed: cratering or the degree of cratering. Did we learn that cratering exists, or did we learn how much cratering there is? I could imagine going with the usage in E even if the craters were already known, but "revealing a degree" shows more clearly that what we discovered washow much cratering there is.
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