Instructions: 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 research strategy in psychotherapy consisting of comparing all the components of one treatment with another in which one of the components of said treatment is eliminated, is known as: 
 Options:  <1> Unique case design. <2> Dismantling. <3> Process study <4> Standardization of treatments. <5> Placebo design
Output:
2