What was the main reason for U. S. involvement in Vietnam? 1. a response to a request for support in the fight against communism.

2. the decision to honor a treaty agreement.

3. the belief that communism would spread in Southeast Asia.

4. an interest in honoring a commitment to the members of the United Nation.

Explanation:

3. America believed in the Domino effect where if one country falls to communism, the neighbouring countries are also at threat of communist revolts.

your answer would be 12 stories

a, c, & d are correct:

they wanted lands to settle the extra population.

they wanted new markets for english goods.

they wanted to avoid civil war.