Answer:
Mountains and seas brought the Greek city-states together. Citizens of city-states put the needs of the city-states above their own. A citizen's strong loyalty to his city-state enabled Greek to unify. The lack of unity among Greek city-states made Greece easier to conquer.
Bill Clinton is known as the 42nd President of the United States and he has been known to have some failures in his reign most especially in terrorism. Based on the given scenarios above, I can say that it was his lack of a quick response to the Rwanda massacre is his administration's worst failure. The answer is option D.
The current president of the United States (2016-) is Donald J Trump
They became the capital of the Roman province of Africa
