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