Which of the following statements best expresses the law of conservation of electric charge for a closed system?
a) Electric charge cannot be destroyed, but it can spontaneously appear in positive‐negative pairs within a closed system.
b) Electric charge in a closed conductor is always uniformly distributed throughout the conductor.
c) The algebraic sum of the electric charges in a closed system remains constant over time.
d) The net charge of a closed system can change only if external work is done on the system.