The correct option is D gravitational force
The force with which the earth pulls objects towards its centre, is called the force of gravity or gravitational force.
If we drop a magnet from our hand, it falls on the ground. This is due to the gravitational force exerted by the earth on the objects around it.
It is not necessary that a magnet can only experience magnetic force. It is also an object having some mass associated with it. Therefore, it will experience the gravitational force.