Answer:
D. any or all of the above
Explanation:
Quotation marks, regardless of the kind of texts they appear in, are primarily used to report a direct speech made by a person, indicate the title of a book or person, cite a direct sentence from another book, or indicate irony. Therefore, in non-fiction texts which are narrations of real events with real characters, the use of quotation marks might be for the purpose of stating the title of a poem, directly quoting a sentence from another book, and reporting a direct speech.