Task: Question Answering
Input (English): Question: Voltammetry of anodic redissolution: 
 Options:  <1> It is always carried out with mercury film electrodes. <2> It uses an oxidation process with chemical agents. <3> It is based on the formation of mercury salts in the electrode. <4> It does not need background electrolyte. <5> It has an electrodeposition stage.
Output (English): 5