Answer:
The correct answer is 'when the field lines are close together'.
Explanation:
Magnetic field lines are pictorial representation of magnetic field around the magnet. They following properties:
- They never intersect with each other.
- The strength of magnetic field is higher when these lines are closer and lower when these lines are apart.
- These lines are continuous with no beginning and and ending, like closed loop.
- They move from north pole to south pole when outside the magnet and move from south pole to north pole when inside the magnet.