Assertion : We cannot think of a magnetic field configuration with three poles. Reason : A bar magnet does exert a torque on itself due to its own field.

Step-by-step solution

Magnetic poles always exist in pairs. However, one can imagine magnetic field configuration with three poles. When north poles of two magnets or south poles of two magnets are glued together, they provide a three pole field configuration. Also a bar magnet does not exert a torque on itself due to its own field.