Instructions: 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'.
Input: Question: A cyclic voltammetry:
Options: <1> It is based on a stationary broadcasting regime. <2> It uses macroelectrodes as working electrodes. <3> He never needs a potentiostatic system. <4> It is always done in a non-agitated solution. <5> It uses a square wave potential format as an excitation system.
Output:
4