Answer: D) A government website on space exploration.
Step-by-step explanation: nonfiction is a kind of writing that is about real events and facts, rather than stories that have been invented. From the given options, the only one that represents an example of a nonfiction source, is the corresponding to option D: A government website on space exploration, because it presents information based on facts and things that really happen, which would help the author to make the elements in his story realistic.