Which half-reaction has the greatest tendency to occur at the anode in an electrochemical cell?

option  B  is  the  answer
 That  is CU2+  oxidized  to  cu, and  Al  reduced   to    Al3+
At  the  the  anode  oxidation  take  place  while at the  cathode  reduction  reaction  take  place.
  copper  metal  is  placed  in  right  hand  side where oxidation  take  place.
  half  reaction  for  oxidation  of  copper  is  as   follows
       cu (s)+3CU^2+  2e-   

The answer should be vaporization 

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