<span>Some causes were:
-Corruption was one of the main reasons for the decline, to gain power a military general might bribe officials and soldiers guarding the wall of the city to overthrow the empire
-Most Byzantine emperors were not capable of keeping a successful army and were often incapable of leading their troops as well
-The Empire lost many important territories
-There are other reasons I cannot really think of right now</span>
The answer to this question is D
