The correct answer is B. France.
Step-by-step explanation
Before the American intervention in the conflict against communism in Vietnam (spread by the Soviet Union in the Indochinese region), there was a presence of European countries like France that were motivated to counteract this political current that had already emerged victorious in China, because it threatened against his colonial interests in this area where he had already territorial control; However, France did not want to invest so many resources of its own for this conflict and decided to ask for help from the United States. So, the correct answer is B. France.