If You Wanted to Increase the Level of Obedience in a Standard

If you wanted to increase the level of obedience in a standard Milgram experiment,which of the following would you do?

A) have a second participant with the teacher who actually flips the shock switch
B) make sure that the learner is in the same room as the teacher
C) have the experimenter give the orders by phone
D) have the experimenter appear to be an ordinary person
E) have the teacher force the learner's hand onto a shock plate