In a Study on Whether People Could Pretend to Be

In a study on whether people could pretend to be hypnotized,what did some of the hypnotized subjects do that the pretenders did not?

A) They made themselves stiff enough to balance with head on one chair and feet on another.
B) ​They tolerated brief sharp pain without flinching or screaming.
C) ​They sat down when told to, without first checking to see whether a chair was present.
D) ​They expressed puzzlement at seeing one person in two places.