The majority of the bombing during Operation Rolling Thunder was launched from sites in Thailand, increasing U. S. military presence that was considered: A) Proclamation
B) Escalation
C) Formation
D) Altercation

B) Escalation

Explanation:

The majority of the bombing during Operation Rolling Thunder was launched from sites in Thailand, increasing U.S. military presence that was considered: "Escalation."

Often referred to as the Policy of Military Escalation, this is a means of committing more and more troops to a war in the hope to facilitate the keeping of international peace and security.

Hence, President Johnson increases the United States military presence in the Vietnam War in 1964, one of which was the act of bombing during Operation Rolling Thunder.