Final answer:
Eric's sexual arousal as an exhibitionist usually increases if his victim shows shock. This reaction tends to validate and enhance the arousal associated with their exhibitionist behavior. It's considered a paraphilic disorder which can lead to counseling or therapy.
Step-by-step explanation:
An exhibitionist, according to psychological definitions, is an individual who experiences sexual arousal from exposing themselves to unsuspecting strangers. In the context of the question, the correct answer is that Eric's sexual arousal usually increases if his victim shows shock (option a). This response is based on the understanding that exhibitionists often seek a reaction from their victims, and the display of shock can validate the exhibitionist's behavior and enhance their arousal. It is important to note that exhibitionism is a type of paraphilic disorder and in some cases, can be considered criminal behavior. Counseling or therapy may be recommended for individuals with such tendencies.