Which set of ordered pairs does not represent a function? A\{(-4, 9), (0, 9), (4, 4), (6, 3)\}{(−4,9),(0,9),(4,4),(6,3)}
B\{(9, 3), (-1, 2), (-6, 4), (9, -6)\}{(9,3),(−1,2),(−6,4),(9,−6)} C\{(1, -8), (-1, 0), (4, -5), (-4, -8)\}{(1,−8),(−1,0),(4,−5),(−4,−8)}
D\{(-4, 7), (4, 0), (-5, 7), (7, -6)\}{(−4,7),(4,0),(−5,7),(7,−6)}

answer: idk

explanation:

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).

in the 1800s, locomotives powered by steam made transportation faster and cheaper. the resulting rapid growth of railroads led to the connection of the atlantic and pacific railroad in oklahoma city in 1897.

in the last years of the century, the improvement of steam-based engines the expansion and growth of railroads. this growth increased when the companies started to build and expand, such as the atlantic and pacific railroad, which connected new mexico with california, and missouri with oklahoma. many of these new networks were built in oklahoma, and these changes transportation henceforward.

the answer is b: an economic crisis throughout the country.