Answer:
In a voltaic cell, the oxidation and reduction of metals occurs at the electrodes. There are two electrodes in a voltaic cell, one in each half-cell. The cathode is where reduction takes place and oxidation takes place at the anode1. The salt bridge is a vital component of any voltaic cell. It is a tube filled with an electrolyte solution such as KNO3 or KCl. The purpose of the salt bridge is to keep the solutions electrically neutral and allow the free flow of ions from one cell to another1.
Based on this information, it seems that answer choice 2- from Mg(s) through the wire to Ni(s) would be correct because oxidation takes place at the anode (Mg(s)) and reduction takes place at the cathode (Ni(s)).