I think the correct answer from the choices listed above is option C. The correct format would be:
According to John Smith, the most common error in solving math questions "relates to the order of operations (9)."
For MLA format, quotations are enclosed within double quotation marks, the author is provided and the specific page. It should be noted that there should be no period after the parenthetical citation.
“in an attempt to save the Chicago Tribune building, men stayed in the roof for as long as possible during the fire, keeping it wet and stamping out cinders.”