In Milgram's Obedience Experiments,"teachers" Exhibited a Somewhat Lower Level of Compliance

In Milgram's obedience experiments,"teachers" exhibited a somewhat lower level of compliance with an experimenter's orders when

A) the experiment was not associated with a prestigious institution like Yale University.
B) the "learner" complained of a slight heart condition just before the experiment began.
C) the "learner" screamed as the shocks became more punishing.
D) the "learner" was in another room where his physical well-being couldn't be observed by the "teacher."