Answer: Option (A) is the correct answer.
Explanation:
Friction is the force which opposes the movement of a substance like wooden block, fluid layer etc or materials which are sliding by touching each other.
According to Newton's first law, an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.
Thus, out of the given options, a force that opposes the relative motion of two objects in contact and sliding past each other best describes friction in the context of Newton's laws.