GMAT Sentence Correction (SC) | Re: Below is a fun SC. Let me know how you all arrived at the

Can someone help me to better understand why A is wrong? More specifically, I am trying to figure out why B is right. I wanted to pick B, but I did not because I felt it needed to say, "Arthur's coffinWAS marked with the inscription." I didn't like A, but not for the same reasons listed asdaagh ....I feel I must be missing something...can someone elaborate for me?
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