Which of these is considered a contact force? a the force between two magnets.
b the gravitational pull of a planet.
c the friction between an object and air.
d The force between two charged particles.

C -) The friction between an object and air.

Explanation:

The frictional force is the force that exists between two surfaces in contact, which is opposed to the movement.

That is, this type of force exists as long as there is physical contact between surfaces.

While the other types of force always act at a separation distance between bodies.