Which statement about the open door notes is true?

The answer is d im pretty sure

I also have to say that it is d

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).

the exclusive possession or control of the supply or trade in a commodity or service.