B

Step 1: Understand the scenario. A bar magnet is falling through a hollow metal cylinder. As it falls, it moves through the magnetic field produced by the cylinder, which induces currents in the metal due to electromagnetic induction.

Step 2: Electromagnetic Induction. According to Faraday's law of electromagnetic induction, a changing magnetic field through a conductive loop induces an electromotive force (emf) in the conductor. The falling bar magnet creates a changing magnetic flux through the metal cylinder, which leads to induced currents (eddy currents) in the cylindrical wall.

Step 3: Opposing force due to Lenz's Law. The direction of the induced current is such that it opposes the change in magnetic flux, according to Lenz's Law. This induced current will produce its own magnetic field that opposes the field of the falling magnet.

Step 4: Resultant acceleration of the magnet. As the magnet falls, gravitational force initially acts on it, contributing a downward acceleration of 'g'. However, the eddy currents create a magnetic drag which opposes this motion. Therefore, the net acceleration of the falling magnet will be less than 'g'.

Conclusion: Over time, as the magnet reaches a steady state (terminal velocity), the acceleration will ultimately become zero, but during the fall, it is initially less than 'g'. Hence, the correct answer is that the final acceleration of the magnet is less than 'g'.
Therefore, the correct answer is B.