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: The prozone effect of a turbidimetric analysis can be detected by measuring the absorbance: 
 Options:  <1> After an ultracentrifugation. <2> Previous concentration of the sample. <3> After dilution of the sample. <4> Once the sample was treated with SDS. <5> Two consecutive times.
Output:
3