What led the us and their allies to get involved in the vietnam war

The  United States and its allies worried that if Vietnam fell to the communists, other countries in Southeast Asia would follow.  This was known as "domino theory" -- that the spread of communism in Vietnam would result in other countries in the region falling like dominoes to the influence of communism.  

President Dwight Eisenhower is the one who initiated the use of the term "domino theory."  In a speech he gave in April, 1954, Eisenhower warned that if French Indochina fell to communism, it very likely could cause a domino  effect in Southeast Asia.  French Indochina is what the region of Vietnam was called during the days of French colonialism there.  The movement against French colonial control was led by Vietnamese nationalist who also happened to be communists.  The Vietamese nationalist / communist movement was led by HoChi Minh.

social contract theory, nearly as old as philosophy itself, is the view that persons' moral and/or political obligations are dependent upon a contract or agreement among them to form the society in which they live

if it were me, i would pick c. c is the best answer because it's basically saying go on a non-violent strike for india