Correct answer: C. primary source document. Primary source is an original document created contemporaneously with the event being researched. It enables researchers to get as close as possible to what actually happened during the historical event (time period). The Apollo 11 flight plan is a historical document that provides direct evidence concerning the topic/event (under research investigation).
<em>The objective of Apollo 11 (launched from Cape Kennedy on July 16, 1969) was to perform a crewed lunar landing and return to Earth. During the exploration, the astronauts were to gather samples of lunar-surface materials. They also were to photograph the lunar terrain, the deployed scientific equipment, and each other.</em>
