How did invading forces contribute to the fall of the byzantine empire

The Byzantine Empire gradually declined and was invaded because of multiple factors, and one of the biggest ones were the invading forces and the damage they were doing. The location of the Byzantine Empire made it very attractive, meaning that it had to defend itself constantly as numerous peoples were attacking it in order to get piece of whole of its territory. The Bulgars were the ones that were making lot of problems and weakening the army in the Balkans, the Muslim Caliphates were constantly attacking from the East, the Turkic people such as the Seljuk Turks were on the move from Central Asia, even the Mongols were making troubles at one point of time, and the final blow to the empire was blown by the Ottomans. One by one, all of these invading forces managed to destroy the army of the Byzantine Empire, and with the black death decimating its numbers, it was written all over that it will be invaded sooner or later.

i beleive a. is the only possible answer

yes based on alexanders actions he deserved the title of "the great". his empire covered about 3,000 miles and he was able to establish the empire over a 13 year period of time. he was able to conquer many different places. he also defeated the persians. he conquered egypt and developed a city and named it after himself.