Question

Which characteristic of Coulomb's law is described or identified by Newton's third law of motion?

A. The proportionality constant k

B. The fundamental unit of charge of an electron or proton

C. The forces on two chargers being equal in magnitude but opposite in direction

D. The relationship between the magnitude of the force and the distance between charges

Answer 1

C is the answer to this question. Hope this helps!

Answer 2

The electrostatic forces between two charged objects ... (as well as the gravitational forces between two masses) ... are equal in magnitude but opposite in direction. (choice-C)

This is exactly what we would expect from Newton's third law of motion.