You will be given a definition of a task first, then some input of the task.
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'.

Question: When an experimental design is carried out, it is fundamentally sought:
Options: <1> Know better the average of the results obtained and repeated in an experiment. <2> Know better the median of the results obtained in an experiment. <3> Identify better the factors that can affect the experiment. <4> To better identify the regression equations in an experiment. <5> To know better the standard deviation of the different data in the experiment.
Output:
3