【单选题】According to the passage,which of the following is one of the primary factors that led researchers studying hypnosis to compare auditory hallucinations and imagined sounds?
A.
The high level of realism involved in auditory hallucinations but not in the experience of external sounds.
B.
The observed similarities between visual and auditory hallucinations in hypnotized subjects.
C.
The fact that both auditory hallucinations and simple imagining are generated by the research subjects.
D.
The blood flow in areas activated by simple imagining but not by auditory hallucination.