While all of the facts in the choices were true for the Byzantine Empire, the reason for the Niki revolt was that the members of the Blues and the Greens had come together in the Hippodrome to compel Emperor Justinian to be merciful to two escaped criminals. Emperor Justinian would not agree to the request.  The crowds rose in revolt against the emperor; they burned down many public buildings in the city, including Saint Sophia. Peasants who had fled their farms as result of heavy taxation joined that day with the demes in what became a major crowd movement, a sort of revolution. The correct answer is B.