Q: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
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.
A:
5