The Gulf of Tonkin Resolution . Ended U. S. Involvement in Vietnam and all of Southeast Asia gave Congressional support to Johnson's Great Society programs was a formal declaration of war by Congress against North Vietnam allowed President Johnson to expand U. S. Involvement in Vietnam

Right choice:

It allowed President Johnson to expand U.S. involvement in Vietnam.

Explanation:

The Gulf of Tonkin resolution was the Congress response to an alleged North Vietnamese attack on U.S. vessels in international waters of the gulf in 1964. It gave great, additional powers to president Lyndon B. Johnson. It authorized him "to take all necessary measures" to repeal attacks on US forces and "to prevent further agression" from the communist North Vietnam. The congressional resolution sanctioned the administration´s intentions to escalate U.S. military involvement in Vietnam, according to historians.

when in doubt choose c

it's what my teacher told my class when we were going into psats