Final answer:
The client with borderline personality disorder is demonstrating the behavior of splitting.
Step-by-step explanation:
The behavior demonstrated by the client with borderline personality disorder is splitting.
Splitting is a defense mechanism commonly associated with borderline personality disorder where the individual sees things in black and white, with no gray areas. This means that they may categorize people as either all good or all bad, and their perception of others can quickly shift from one extreme to the other.
In this case, the client dramatically expresses strong positive feelings about the nurse they are talking to at the time, while simultaneously devaluing and dismissing the other nurses.