Answer: b) Dissociation theory
Explanation:
Dissociation theory is defined as the concept that states that a hypnotized person is subjected to separate its consciousness into streams.Thus, control system of brain is voluntarily split.
According to the question,dissociation theory of hypnosis is describing situation of hypnotized Tiffany ,where she feels as if some thinking ability and control part of her brain was monitored by hypnotist.
Other options are incorrect because role theory, state theory and alter theory is not suited with situation of Tiffany's hypnosis. Thus, the correct option is option(b).