Answer:
Option D, He was the first U.S. President to send troops to Vietnam and increased U.S. involvement in the Vietnam War
Step-by-step explanation:
Through the new foreign policy, President Johnson allowed the American troops to involve in Vietnam war. Followed by foreign policy, in 1964 Gulf of Tonkin Resolution was passed by Congress to allow President Johnson to use military force in Southeast Asia without any official declaration of war.
Hence, option D is correct