A nurse is caring for a client who has pneumonia. Which of the following actions should the nurse take to promote thinning of respiratory secretions?

Rationale: A. Ambulation helps with lung expansion but does not directly thin secretions. B. Incentive spirometer use improves ventilation and prevents atelectasis but does not specifically thin secretions. C. Coughing and deep breathing help mobilize secretions once loosened, but they do not thin them. D. Increasing fluid intake hydrates the respiratory tract and helps thin secretions, making them easier to expectorate — this is the most effective action.