What was a major reason Constantinople fell to the Ottoman Turks in 1453?

Question

A.
The city was weak after suffering an outbreak of plague.
B.
The city was betrayed after its ruler accepted a bribe.
C.
The city was weak after many years of constant attack.
D.
The city was betrayed after the army changed sides.

Answer 1

B. The city was betrayed after its ruler accepted a bribe.