Answer:
your answer would be c the third one
Explanation:
In the Age of New Imperialism that began in the 1870s, European states established vast empires mainly in Africa, but also in Asia and the Middle East. - https://www.tamaqua.k12.pa.us/cms/lib07/PA01000119/Centricity/Domain/119/TheAgeofImperialism.pdf
B) Preventing the spread of communism
The role of the united state in Vietnam war began after the world warII. US mission was to restrict the communist domination that was present in Vietnam government, this was because communism could easily spread to the Neighbouring countries which would result to a change in the balance of power throughout Southeast Asia.
