GMAT Sentence Correction (SC) | Re: Carbon-14 dating reveals that the megalithic

Carbon-14 dating reveals that the megalithic monuments in Brittany are nearly 2,000 yearsas old as any of their supposed Mediterranean predecessors.

A. as old as any of their supposed
B. older than any of their supposed
C. as old as their supposed
D. older than any of their supposedly
E. as old as their supposedly

'as old as' is wordy and does not provide clear comparison - A,C,E are out

Out of B & D, supposedly is an adverb while we need an adjective to modify noun 'predecessors'.

IMO
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