A voltaic cell spontaneously converts chemical energy to electrical energy. The correct option among all the options given in the question is option "2".
Actually voltaic cell is an electrochemical cell that
converts the chemical contained within it by the process of chemical reaction
to produce electrical energy. The voltaic cell contains an anode and a cathode.
Anode is an electrode where the oxidation occurs and cathode is the electrode
where reduction occurs. The oxidation and the reduction part occurs in two
separate parts of the cell known as half-cell.