Answer:
Among the options available with this question, the right choice is:
A. Gulf of Tonkin Incident
Explanation:
It is a major 1964 event that led to a larger military involvement by the United States in the war in Indochina. An American vessel was attacked by North Vietnamese boats in the Gulf of Tonkin, and the Lyndon B. Johnson administration asked Congress to give it more, greater powers to act in Southeast Asia.
The other events: B. Martin Luther King, Jr. assassination C. Robert Kennedy assassination D. Tet Offensive, all of them happened in 1968.
