The magnetic fields are strongest at point A and weakest at point C. The magnetic field lines can be used to indicate the strength of a magnet or magnetic field. The closer together the magnetic field lines the stronger the magnetic field.
Explanation:
The magnetic field line also shows the direction of the magnetic field, hence they are also considered vector fields because they have magnitude and direction. They usually have an arrow indicating that the field lines are moving from the north pole to the south pole. The lines also never cross and are always in closed loops.