The correct answer is A. Truman desegregates the United States Armed Forces.
Explanation
Harry S. Truman was president of the United States, after the death of President Frankin Delano Roosevelt between 1945 and 1953. One of his actions as president was the signing of Executive Order 9981 with which he sought to abolish racial discrimination in the Armed Forces. This action gave him the support of a large faction of the civil rights movement of the Afro-American community, as well as reinforced this movement during the fifties. Therefore, the correct answer is A. Truman desegregates the United States Armed Forces.