The correct answer is B) deploy federal troops to the city.
In the case of violent riots in a major American city, the President of the United States can deploy federal troops to the city.
For instance, we have the case of President John F. Kennedy and the way he acted when confronted with the violent riots in the University of Mississippi and the University of Alabama in the 1960s. In 1962, Kennedy sent federal troops to Oxford, Mississippi to control the riots. The white students did not want that the black students enrolled in the university. The case of the University of Alabama was similar. On June 3, 1963, Kennedy sent federal troops to Tuscaloosa, Alabama to control the riots.