The nurse receives four clients in the emergency department from triage at the same time. Which client requires the nurse's immediate attention?

A. An acute allergic reaction, especially if involving airway compromise, can be life-threatening and requires immediate attention. B. The client with lung cancer and a cough is concerning but not as urgent as an acute allergic reaction. C. Dyspnea on exertion needs evaluation but is not as urgent as a possible airway issue. D. A sinus infection with nasal discharge is typically not an emergency.