Final answer:
To learn about the origins of the Peace Corps program, one should refer to the heading. (Option 'D) The birth of a volunteer program,' where the program's conception and development are likely discussed.
Step-by-step explanation:
The Peace Corps program got its start under the heading The birth of a volunteer program. It was created after World War II, when Americans wanted a peaceful way to help other nations.
The program was first introduced by Democratic Senator Hubert H. Humphrey in 1957, but gained popularity among American voters when John F. Kennedy talked about it during his presidential campaign in 1960.
Kennedy's famous quote, 'Ask not what your country can do for you—ask what you can do for your country,' captured the spirit of the Peace Corps.