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: In its origins, the technique of Systematic Desensitization was explained from: 
 Options:  <1> Operant conditioning. <2> Conditioning in a single trial. <3> Classical conditioning. <4> Vicar conditioning. <5> Instrumental conditioning.
