Which of the following types of microphones does not require power to operate?

The dynamic microphone is the type that does not require power to operate. It functions based on electromagnetic induction, where sound waves cause a diaphragm to move within a magnetic field, creating an electrical signal. Because of this intrinsic design, dynamic microphones are self-sufficient and do not need external power sources like batteries or phantom power, which are often required by other types of microphones such as condenser microphones.

Condenser microphones, in contrast, rely on an electrically charged diaphragm and require power to maintain that charge, typically provided by phantom power from a mixer or an audio interface. Directional and omni-directional microphones refer to their pickup patterns and can be either dynamic or condenser types. Therefore, among the choices listed, only the dynamic microphone is able to function independently of an external power source.