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'.
Q: Question: Regarding the molding technique, which of the following characteristics is TRUE?
Options: <1> A structured environment is required. <2> It can be carried out forward and backward. <3> It implies the successive application of reinforcement and extinction. <4> The successive approximations are necessarily part of the final behavior. <5> The goal behavior can be simple or complex.
A:
3