Tangential frictional force is the correct answer. This force acts parallel to the surface of the application of friction.

Explanation:
Frictional force is a force that opposes the relative motion or tendency of motion between two surfaces in contact. It arises due to the irregularities present on the surfaces in contact.

When an object is in contact with a surface and there is a force acting on it, the frictional force comes into play. The direction of the frictional force depends on the direction of the applied force. The two types of frictional forces are static friction and kinetic friction.

Static friction comes into play when there is no relative motion between the surfaces in contact. It prevents the object from starting to move. Once the applied force exceeds the maximum static friction, the object starts moving and kinetic friction comes into play.

The direction of the frictional force is always opposite to the direction of the applied force. This is known as the direction of the frictional force. However, the frictional force acts tangentially to the surface of application, not perpendicular or parallel.

- Perpendicular: The normal force is the force exerted by a surface to support the weight of an object resting on it. It acts perpendicular to the surface. The frictional force does not act in this direction.
- Parallel: The parallel direction would be the same as the direction of the applied force. However, the frictional force opposes the applied force and acts in the opposite direction.
- Normal: The normal force and the frictional force are often perpendicular to each other, but they are not the same.

Therefore, the correct answer is tangential, as it correctly describes the direction of the conservative frictional force.

B. non conservative force