Answer:
The correct answer is letter "B": Authorized the president to take "all necessary measures to repel armed attack" in Vietnam.
Step-by-step explanation:
The Gulf of Tonkin Resolution (1964) granted President of The United States Lyndon B. Johnson to “take all necessary measures to repel any armed attack against the forces of the United States and to prevent further aggression” by communist North Vietnam. By the beginning of August 1964, two U.S. destroyers (U.S.S. Maddox and U.S.S. Turner Joy) stationed in the Gulf of Tonkin were attacked by North Vietnamese forces. It provoked the U.S. Congress to raise American military presence in that Asian area thanks to the Gulf of Tonkin Resolution. It was the official document that approved the full involvement of the U.S. in the Vietnam War.