What was the most common argument used by the US presidents of the 1960s and 1970s favoring military involvement in Vietnam?
A.
They argued that they wanted to stop the Vietnamese effort to create a democratic nation.
B.
They claimed that the South Vietnamese were invading North Vietnam illegally, which warranted US involvement.
C.
They claimed the US must fight in the Vietnam War to stop the potential spread of communism.
D.
They argued that they wanted to assert executive authority over legislative powers by entering the war.
its is C