Which factor most contributed to the development of feudalism in Western Europe

the conditions that made the byzantine empire vulnerable to attacks by the muslin turks were the sack of constantinople by western crusaders, the conquests of the sultanate of rum, presence of rival kingdoms and finally the set up of fiefdoms at the empire which were owned by the ghazis (turkish warriors).

when in doubt choose c

it's what my teacher told my class when we were going into psats

i believe it was the shinto