Answer:
The correct answer is A. The infliction of heavy casualties upon the communists did not bring about a US victory in Vietnam.
Explanation:
The Vietnam War took place in and around Vietnam from 1955 to 1975. The main warring parties were North Vietnam and the Viet Cong, against the USA and South Vietnam. It ended with North Vietnam's victory and the United States' first military defeat in its history.
After the partition of Vietnam in 1954, a civil war that lasted from 1955 to 1964 broke out in South Vietnam: the Viet Minh, from which the Viet Cong emerged in 1960, wanted to overthrow the country's anti-communist government and reunite it with the north. The Viet Cong was supported by Communist-ruled North Vietnam under HoChi Minh, while South Vietnam was increasingly supported by the USA. The successive US governments under presidents Eisenhower, Kennedy, Johnson and Nixon feared, based on the so-called domino theory, that Vietnam could put all of Southeast Asia under the control of communist governments.
After the Tonkin Incident of 1964, President Lyndon B. Johnson ordered the bombing of North Vietnam for the first time in February 1965. Since March he sent a great number of troops to combat the Viet Cong to South Vietnam. The Soviet Union and the People's Republic of China then supported North Vietnam. Six states took part in the conflict on the side of the USA and South Vietnam with their own troop contingents. From 1964 the fighting spread to Laos and from 1970 to Cambodia.
After the communist's Tet offensive, Johnson stopped bombing until November 1968. His successor Richard Nixon gradually pulled the US troops out of South Vietnam from 1969, but at the same time extended the war to Cambodia. After another, unsuccessful American bombing campaign by the military, the US government concluded a ceasefire with North Vietnam in January 1973. By March 29 this year, all US troops had withdrawn and North Vietnam released all American prisoners of war. On May 1, 1975, the war ended with the conquest of the South Vietnamese capital Saigon by North Vietnamese troops.