Which of the following is NOT a conductor?

Correct option is A

Hard rubber is NOT a conductor.
 Conductivity is the ability of a material to allow the flow of electric current.
 Metals are generally good conductors of electricity, while nonmetals are poor conductors.
 Among the options given, Copper, Silver, and Nickel are all metals and are good conductors of electricity.
 Hard rubber, also known as ebonite, is a nonmetal and an insulator.
 Uses - in the manufacture of electrical insulators, such as in switches and circuit breakers, to prevent the flow of electric current where it is not needed.