Final answer:
The client using dissociation as a defense mechanism is the one who talks about their traumatic experiences with emotional detachment, as it allows them to mentally escape from the emotional impact of the trauma.
Step-by-step explanation:
The client using dissociation as a defense mechanism is a client who is talking about traumatic experiences with emotional detachment. Dissociation is a complex psychological process often used as a coping strategy to disconnect and detach from emotional involvement in traumatic experiences. By doing this, the individual can mentally escape from the emotional impact and intensity of the trauma. Dissociation can manifest in various forms, such as amnesia, depersonalization, derealization, identity confusion, and identity alteration. In contrast, the other behaviors mentioned in the choices, such as expressing anger and frustration, avoiding social interactions, and engaging in excessive handwashing, could represent different defense mechanisms or behaviors but do not specifically characterize dissociation.