Final answer:
Option 2. "This is common behavior that is expressed when the hospitalized child is stressed or anxious." is the correct response.
Step-by-step explanation:
Option 2. "This is common behavior that is expressed when the hospitalized child is stressed or anxious." is the correct response by the nurse. When a child undergoes hospitalization or experiences a significant change in their environment, they may exhibit regression or resistance to previous learned behaviors, such as potty training. This behavior is a common response to stress and anxiety, and it is important for parents to provide reassurance and support to help the child re-establish their routine and regain confidence.