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
Answer - B. why not D?
(I am not sure about the source of this question. I found it in my old notes)