Assertion (A): Magnetic field lines never intersect each other.

Reason (R): If they intersect, then at the point of intersection, the compass needle would point towards two directions, which is not possible.

According to the NCERT textbook:

1. Assertion (A) is True: Magnetic field lines are continuous closed curves representing the direction of the magnetic field at any point. No two magnetic field lines are ever found to cross or intersect each other.
2. Reason (R) is True: The direction of the magnetic field at any point is the direction in which the north pole of a compass needle points. If two field lines were to intersect at a point, it would mean that at that specific point of intersection, the magnetic field has two different directions. Consequently, a compass needle placed at that point would have to point in two directions simultaneously, which is physically impossible.

Since the Reason correctly explains why the field lines can never intersect, both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).