GEOLOGY

Detailed explanation-1: -force of friction is the contact force.

Detailed explanation-2: -Muscular and friction are the two forces in the above options that require contact with the objects for their effect. Electrostatic and gravitational forces are non-contact forces and can act from a distance.

Detailed explanation-3: -Gravitational force is an example of a non-contact force.

Detailed explanation-4: -Force of friction is a contact force, i.e., it always acts when the bodies are in contact.

Detailed explanation-5: -A force that can cause or change the motion of an object by touching it is called Contact Force. For example, muscular force, frictional force, spring force, tension force, air resistance force etc.