Final answer:
The response that exemplifies active listening acknowledges the patient's feelings, confirms understanding, and suggests a proactive step.
Step-by-step explanation:
The example of active listening provided by the medical assistant is: "I understand that waiting can be frustrating. Let me check with the doctor to see if there's any delay." This response acknowledges the patient's feelings, restates them to show understanding, and proposes a clear action to address the concern, which are all indicators of active listening.