GMAT Sentence Correction (SC) | Re: The remarkable similarity of Thule artifacts throughout a vast region

Can you please provide a definition (like a dictionary one) for "explained as" and for "explained by"?
Are they both phrasal verb?

I still don't get why answer A is wrong. For me "can be explained as" means "we can explain it with the following reason...", "we can say it is due to...."

Thanks in advance

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