The MLA style specifies that a superscript be used for a note reference mark to signal an explanatory note exists either at the bottom of the page as a(n) __________.

• A. footnote or at the end of the document as a startnote
• B. headnote or at the end of the document as an endnote
• C. footnote or at the end of the document as an endnote
• D. headnote or at the end of the document as a startnote