The correct answer is b. the gulf of tonkin and the gulf of thailand. i picked d and got it wrong and it showed me the right answer b.

couples could only have one child to reduce the population growth.

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).