A nurse is caring for a client who is taking montelukast. Which of the following outcomes indicates a therapeutic effect of the medication?

The correct answer is C: The client experiences an increased ease of breathing. Montelukast is a leukotriene receptor antagonist used to treat asthma and allergic rhinitis. The therapeutic effect of montelukast is to reduce inflammation in the airways, leading to improved breathing. Therefore, an increased ease of breathing indicates that the medication is working as intended. Options A, B, and D are incorrect because montelukast does not affect seizure thresholds, muscle pain, or platelet count.