Final answer:
The nurse is in the evaluation phase of the nursing process, as she is checking the client's response to the bronchodilator treatment.
Step-by-step explanation:
The nurse is evaluating the efficacy of the treatment by asking the client if their breathing has improved after administration of the inhaled bronchodilator. The evaluation phase of the nursing process involves determining the client's response to the nursing interventions and if the goals of the interventions are being met. It is an essential step that follows the implementation phase, where the nurse administers or carries out the prescribed treatments or interventions.