The correct answer is B. The Vietnam War lasted from 1959 to 1975.
Armed actions had been taking place since November 1, 1955; but it was in 1959 when the real struggle began. At that time, former Viet Minh guerrillas, Buddhist monks, peasants and several other groups began to integrate what would later be called the National Liberation Front.
It is estimated that between 3.8 and 5.7 million people died in total. The United States counted 58,159 casualties.