It happens in accordance with the Lenzs law. The end A becomes north pole, to oppose the motion of the magnet.

Explanation

Lenz’s law states that

The induced electromotive force with different polarities induces a current whose magnetic field opposes the change in magnetic flux through the loop in order to ensure that original flux is maintained through the loop when current flows in it.Lenz’s law is based on the law of conservation of energy. From the definition of Lenz’s law, we know that the induced current is always opposed by the cause that produces it. Therefore, there is extra work done against the opposing force. The work done against the opposing force results in the change in the magnetic flux and hence the current is induced. The extra work done is known as electrical energy which is the law of conservation of energy.