Final answer:
A punch line is a humorous or clever remark that shifts the meaning in an unexpected way.
Step-by-step explanation:
A punch line is a humorous or clever remark that is typically used to conclude a joke or a humorous story. It is known for its surprise element and for subverting the expectations of the listener. Option (c) - It shifts the meaning in an unexpected way - best describes a punch line. It is the punch line's ability to abruptly shift the meaning or create an unexpected twist that brings out its humor.