What are two causes of friction

Surface roughness and deformations

Explanation:

Friction is a force that resists the relative motion between two objects or materials. The causes of this resistive force are molecular adhesion, surface roughness, and deformations. Adhesion is the molecular force resulting when two materials are brought into close contact with each other

Answer:friction is caused by the roughness of the surface, combined with the attractive forces between the body and the surface on which it is placed. Both the things play their roles in creating the effect of friction.