The presence of a magnetic field can be detected by which of the following instrument?

• A voltmeter is a device which is used to measure the voltage in a circuit.
• Ammeter and Galvanometer are devices which are used to measure the current in a circuit.
• The Magnetic compass is an instrument which has its own natural magnetism. 
• The presence of a magnetic field can disturb the magnetic field produced by the compass and exert a magnetic force on the magnetic needle. This can cause the movement of the magnetic needle of a compass.
• Therefore, we can detect the presence of a magnetic field from the movement of the compass needle.

Hence, 'Magnetic Compass' is the correct response.