Answer :
It's he established a policy that would prevent any expansion of communism.
The correct answer is B) he developed a more limited and strategic policy for the use of American troops.
The Vietnam War influenced the foreign policy of Richard Nixon in that he developed a more limited and strategic policy for the use of American troops.
President Nixon was very interested in foreign policy. Indeed, he wanted to be in control of the United States foreign policy during his tenure at the White House. He favored the counseling of Henry Kissinger –his assistant if foreign affairs- over his Secretary of State (William Rogers) or his Secretary of Defense (Marvin Laird). In the case of the usage of the military in Vietnam, Richard Nixon developed a more limited and strategic policy for the use of American troops.