Magnetic field lines at north pole of a magnet are:

Correct option is D

Magnetic field lines at the north pole of a magnet are lines emerging from the pole. 

Here are some other facts about magnetic field lines: 

• The magnetic field lines of a magnet emerge from the north pole and merge at the south pole.
• The magnetic field lines try to form closed loops from pole to pole in a single bar magnet.
• The magnetic field lines never cross each other.
• The strength of a magnetic field can be observed from the closeness of the field lines.
• The direction of the magnetic field is the direction in which a north pole of a compass needle moves inside it.