The correct option is C Graphite
Graphite is an allotrope of carbon which is a non-metal. It is formed by carbon bonding in hexagonal arrays in which every carbon atom is covalently joined to three other carbon atoms. Since all the carbon atoms in graphite are bonded to three other carbon atoms and the fourth electron is free to move the mobility of the free electron makes graphite a good conductor of electricity.
Sodium, copper and iron are metals which have free electrons and can conduct electricity.