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: A primary standard solution in a titration should not: 
 Options:  <1> Be prepared from a high purity reagent. <2> Have an exactly known concentration. <3> Keep your composition over time. <4> React instantly. <5> Give rise to secondary reactions.
