Final answer:
A biography of a president is an example of a secondary source as it provides an interpretation of their life and actions.
Step-by-step explanation:
A secondary source is a document or piece of information created after an event has taken place, by someone who was not directly involved. Therefore, the correct example of a secondary source from the given options is Option C: A biography of a president. Biographies are written by authors who were not present during the president's lifetime and provide an interpretation of their life and actions.
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