An autobiography's primary purpose is to but it is also considered a. be factual; creative b. inform; persuasive c. entertain; factual d. all of these

(C) An autobiography's primary purpose is to entertain but it is also considered factual. 
This is because the story is about the author, and the author is the one writing the story. The author will try to entertain the readers about his life and story, but it is also factual because it is true.