In a PMMC instrument, swamping resistance is employed to:

The correct answer is option 2.

Permanent magnet moving coil instrument (PMMC)

• These instruments are used to measure DC quantities.
• Its working principle is similar to a motor i.e. when a movable coil is placed in the magnetic field it experiences a torque and moves.
• Here, permanent magnets are used to produce the magnetic field, and hence the instrument is called a permanent magnet moving coil instrument.
• Whenever the coil moves in the magnetic field, the pointer shows deflection and the deflection of the pointer is directly proportional to the coil current
• It has a uniform scale.
• The controlling torque is provided by either spring or gravity control.
• The damping torque is provided by the eddy current damping.

Errors in PMMC Instrument

• The basic sources of error in PMMC instruments are friction, temperature, and aging of various parts.
• To reduce the frictional errors ratio of torque to weight is made very high. 
• The swamping resistance is compensate the error due to temperature variations.