Task: Question Answering
Input (English): 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.
Output (English): 3