单选题 The research described in the passage is primarily concerned with answering which of the following questions?

• (A) How can researchers reproduce the useful effects of hypnosis in a medical setting?
• (B) How are experiments devoted to disproving the "vivid imagination" objection to hypnosis different from those devoted to disproving the "placebo effect" thesis?
• (C) What research guarantees the reality of the effects that hypnosis has on brain activity, and what is their causal mechanism?
• (D) What technical advances have permitted researchers to reject skeptical explanations of the phenomenon of hypnosis?
• (E) What relationship does brain activity have to the subjective experience of the hypnosis phenomenon?