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: What characterizes the objective techniques of psychophysiological evaluation?
Options: <1> They are tests with a high ecological validity. <2> Environmental factors (e.g., light, temperature) can affect the reliability of the record. <3> The anxious subjects usually have the same level of activation as the non-anxious ones. <4> Subjects with different anxiety disorders usually have similar patterns of activation at baseline. <5> Subjects with different anxiety disorders usually have similar responses to different stimuli.
Output:
2