Definition: 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: In a potentiometry at zero intensity the electrode: 
 Options:  <1> Indicator always measures balance potentials. <2> Indicator measures the half-wave potential. <3> Indicator can measure a mixed potential. <4> Reference is always a calomel platinum electrode. <5> Indicator is always a platinum electrode.
