Example when we walk,our feet is parallel to the road. so option b is correct.

Friction is a force that opposes the relative motion or tendency of motion between two surfaces in contact. It acts in the opposite direction to the applied force and is parallel to the contact surface. Therefore, the correct answer is option 'B': the force of friction between two bodies in contact is parallel to the contact surface.

Explanation:
The force of friction arises due to the interaction between the atoms or molecules on the surfaces of two bodies in contact. These atoms or molecules exert attractive forces on each other, which resists the motion or tendency of motion between the two surfaces.

Friction can be categorized into two types: static friction and kinetic friction. Static friction is the force that prevents an object from moving when an external force is applied to it. Kinetic friction, on the other hand, is the force that opposes the motion of an object when it is already in motion.

The force of friction always acts parallel to the contact surface between the two bodies. This means that if the two bodies are in contact horizontally, the force of friction will act horizontally as well. Similarly, if the two bodies are in contact vertically, the force of friction will act vertically.

The direction of the force of friction is determined by the direction of the applied force or the motion of the object. If the applied force or the motion is in the positive x-direction, the force of friction will act in the negative x-direction. If the applied force or the motion is in the negative x-direction, the force of friction will act in the positive x-direction.

In summary, the force of friction between two bodies in contact is parallel to the contact surface and acts in the opposite direction to the applied force or the motion of the object.