Sentence Correction

Hi Friends,

I need your help in understanding the difference between the two questions. Most importantly between two choices.

Recent anthropological studies reveal that the entombed mummy found in Jordan is almost 5,000 years as old as any of its purported Egyptian ancestors.

A) as old as any of its purported
B) older than any of its purported
C) as old as its purported
D) older than any of its purportedly
E) as old as its purportedly

Answer is B
Most importantly my doubt is between B and D.

I have a similar question in comparison to above one but not sure why correct answer is correct.

A new analysis of ruins on the northernmost tip of Newfoundland reveals that the Viking settlement there is almost 600 years as old as the supposedly first North American colony.

A) as old as the supposedly
B) older than the supposedly
C) as old as the supposed
D) older than their supposed
E) as old as its first supposedly

Answer is B
What is the difference between B and D. In my opinion i see their in D that makes a difference but now what about supposedly and supposed.

Please help in understanding the difference between these two choices.

Thanks & Regards
Vinni