In 1963, the governor of Alabama, George Wallace, tried to physically stop three African-American students from registering at the University of Alabama. President Kennedy ordered the Alabama National Guard to force Wallace to move aside and allow the students to register. Why did President Kennedy take this action?
A. The state judicial branch refused to comply with an executive order.
B. The state executive branch refused to comply with a federal court ruling.
C. The federal judicial branch refused to comply with a ruling by the state judicial branch.
D. The federal legislative branch refused to comply with a state executive branch decision.