The psychiatric nurse is caring for clients on an adolescent unit. Which client requires the nurse's immediate attention?

A. Refusing one meal is concerning for anorexia nervosa, but it does not pose an immediate safety threat and can be monitored closely. B. Being yelled at may cause distress but is not an urgent threat to safety or health. C. Pacing in a client with bipolar disorder can signal severe agitation, risk of aggression, or inability to control impulses, requiring immediate intervention to prevent harm. D. Refusal to participate in group signals withdrawal or low mood, but it is not immediately dangerous.