A one-day post-operative client complains of having a lot of mucus in his throat and is having a difficult time moving it to his mouth so he can spit it out. The client is reluctant to perform coughing and deep breathing due to pain. Based on the data, the priority problem that the nurse could assign to this patient is:

D. This refers to the inability to clear secretions or obstructions from the respiratory tract to maintain airway patency. Based on the client's complaint of difficulty moving mucus from the throat to the mouth for expectoration, ineffective airway clearance is the priority problem. The client's reluctance to cough and deep breathe due to pain further exacerbates this issue, as effective airway clearance is crucial for preventing complications such as respiratory infections or atelectasis post-operatively.

A. Activity intolerance refers to insufficient physiological or psychological energy to endure or complete required or desired daily activities. In the case of a one-day post-operative client experiencing difficulty clearing mucus, activity intolerance is not the priority problem. The client's main issue is related to respiratory function and airway clearance rather than overall activity tolerance.

B. This refers to abnormal respiratory rate, depth, or rhythm that does not provide adequate ventilation. While the client's complaint of difficulty moving mucus and reluctance to cough or deep breathe suggests some respiratory discomfort, the main issue appears to be the inability to effectively clear airway secretions rather than an overall ineffective breathing pattern.

C. This refers to the inability to exchange oxygen and carbon dioxide across the alveolar-capillary membranes. While mucus in the throat can potentially affect gas exchange if it obstructs airflow significantly, the client's primary complaint is about difficulty clearing mucus rather than signs and symptoms of inadequate oxygenation or ventilation.