Sentence Correction

Carbon-14 dating reveals that the megalithic monuments in Brittany are nearly 2,000 years as 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

OA - B


When to use what between Adverb and adjective... Got confused in B and D

Mediterranean predecessors is noun

So, it is B not D