Answer:
A. simple to construct and easy to repair
Step-by-step explanation:
A dynamic microphone works on the principle of electromagnetic principle. A diaphragm is attached to a coil of wire which helps in producing sound. Responding to the sound waves, the coil of the wire is vibrated by the diaphragm. A magnetic field is created by the magnet which is present inside the coil of wire. The electrical signal is generated in response to the motion of the coil. The speed of the motion produces the amount of the current.
Since the construction of a dynamic microphone is easier as compared to any other microphone, John is likely to opt to build one.