Which of these is an example of a primary source of historical research on the Civil Rights Movement in the United States in the 1950s and 1960s?
a) A history journal article about how Black churches impacted the Civil Rights Movement
b) A modern Hollywood movie about the civil rights marches in the American South
c) A 1963 audio recording of Martin Luther King Jr., a movement leader, giving a speech on civil rights
d) A present-day magazine article on cultural fashions in the 1960s