Which of the following is correct according to MLA format? A) The works cited should appear as footnotes within your essay. B) Only the first...

Choice "A" is wrong.  MLA formatting stopped using footnotes in 1988.  Since then MLA has recommended the use of parenthetical citations instead.  

Choice "B" is even more incorrect.  Only citing the first quote in an entire essay is crazy.  Every single time that you use a quote from a new source, that source needs to be identified within a parenthetical citation.  A writer also needs to re-identify a source when he/she switches back to it after using a different source previously.  

Choice "D" is also wrong.  I don't even know exactly what it means.  I do know that your citing needs to be as specific as possible, which means cite what you use. 

Choice "C" is the correct choice.  Signal phrases alert your reader to the fact that the following quote is not your original thought.  They key the reader into a coming quote and identify which source that quote is coming from.  Signal phrases typically include the name of the author of the quote and an action verb.  For example: Butch Sundance states ". . ." (14).  Without the signal phrase proceeding the quote, the quote appears to be a "floating quotation."  Floating quotations are quotations that appear to be used at random without any explanation.