Final answer:
The nurse is thinking critically when questioning a physician about the rationale for an order, demonstrating active engagement and analytical evaluation to form professional judgments.
Step-by-step explanation:
The situation that demonstrates a nurse is thinking critically would be A. Questioning a physician regarding the rationale for an order. This example shows that the nurse is not only following orders but is also actively engaged in the process by seeking to understand the reasoning behind the treatment plan. This form of inquiry is a cornerstone of critical thinking, as it involves analyzing and evaluating information to form a judgment. By questioning, the nurse is demonstrating a desire to comprehend fully and contribute to the patient's care, ensuring that all actions align with professional standards and the latest medical evidence.
CPR on a pulseless, non-breathing patient (Option B) is a direct response to a life-threatening situation and does not necessarily reflect critical thinking as much as it does proper training and execution of protocols. Teaching coworkers (Option C) and attending class on time (Option D) are responsible actions but do not directly signify the application of critical thinking in the context of individual patient care.