The correct answer is B) U. S. military serving in the Korean Conflict.
The institution President Harry Truman is credited with integrating was the U. S. military serving in the Korean Conflict.
On July 26, 1948, United States President Harry S. Truman issued the Executive Order 9981 to eliminate all kind of discrimination in the US Armed Forces, that basically included the Army, the Navy, and the Air Force. With this executive order, President Truman integrated the military and prohibited segregation in the military.