Choose the correct statements. The coefficient of static friction depends upon (A) The materials of body in contact (B) quality of matching of the surface in contact (C) presence of foreign matter between the surfaces (D) area of the surfaces in contact

Friction force depends on the contact material whose electrostatic interaction decides the friction coefficient.

Quality of machining of the surface in contact decides the force example friction force is different of smooth source and rough surface. 

Presence of foreign matter between the surfaces interferes with the electromagnetic force between two surfaces that changes the friction coefficient.

Surface area does not affect the friction force.