Answer:
D. It was divided into 2 separate countries.
Step-by-step explanation:
The Battle of Dien Bien Phu was a fight for power in the Southeast Asian nation of Vietnam, at that time French Indochina. The fighting between the French Union's army and the Viet Minh communist revolutionaries would take about two months, resulting in the victory for the Vietnam revolutionaries.
After the defeat of the French were defeated, and their stronghold at Dien Bien Phu fell, the French retreated out of the region. This led to the advancement of the Vietnamese revolutionaries. But the effect of this battle was that Vietnam was separated into two countries, the Democratic Republic of Vietnam (North Vietnam) and the State of Vietnam (South Vietnam).
Thus, the correct answer is option D.