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: To observe the bacterial capsules in a clear field microscope, a stain is made: 
 Options:  <1> Resistant acid <2> From Leifson. <3> Simple. <4> Negative. <5> Differential.
Output:
4