Final answer:
The female client's calm and quiet demeanor following a traumatic event like sexual assault suggests that she is likely using the defense mechanism of denial, which allows her to temporarily block out the distressing reality.
Step-by-step explanation:
In the scenario provided, the female client who has been sexually assaulted and is sitting calmly and quietly in the examination room is likely exhibiting the defense mechanism of denial.
Denial is a defense mechanism where a person refuses to accept reality or facts, blocking external events from awareness. If some situation is too much to handle, the person simply refuses to experience it. As with other defense mechanisms, it operates unconsciously and helps reduce anxiety in the short term.