Which of the Following Methods Is the Most Appropriate One

Multiple Choice

Which of the following methods is the most appropriate one for 'proving' someone cheated on a multiple choice exam who was allegedly looking at someone else's paper?

A) Examine the two papers and see how many questions they both got wrong, and how many times the same wrong answer was chosen for those questions.
B) Take the student's paper that was allegedly copied from (student X) and compare it to all other students' papers in the class.Take the number of answers that each student matched with student X and make a histogram.Then see where the alleged cheater fell on the resulting histogram.
C) Neither of these methods is appropriate.There is always a chance that two people could have the same answers but no cheating was going on.
D) Both of these methods are equivalent, so either one is appropriate.