What force resists relative motion between two bodies in contact?

Friction is the force that resists relative motion between two bodies in contact. It occurs when two surfaces interact and can be affected by factors such as the materials involved, their surface textures, and the force pressing them together. This force plays a vital role in everyday activities, such as walking, driving, and holding objects, as it allows for grip and control.

Gravity acts as a force that pulls objects toward each other based on their masses but does not directly resist motion between surfaces. Tension refers to the force transmitted through a string, rope, or cable when it is pulled tight, and it is not applicable to surfaces in contact. Compression is a force that pushes or compresses materials together but similarly does not resist relative motion between surfaces. Thus, friction is the correct answer as it specifically addresses the resistance encountered by two surfaces in contact.