GMAT Sentence Correction (SC) | The people of the ancient Near

Hi Expert,

I didn't get the line of reasoning here.

IMO, D has to be the correct one over here.

My Line of thought-the action of "separated" occurred before anything else, therefore, its imperative and only logical to make that verb past perfect.
Creator had separated the 2 skies and then the Earth's dry land appeared.
Use of "first" before "Appeared" makes it a verb that took place before the verb "Believed".

Where am i wrong on this?

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