Why did the platation owners think they needed slaves

because it was a more efficent way to get work done, if they didnt want to do the dirty work.

answer; i believe that the correct answer is (c) arctic tundra;

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).