Voluntary behaviors that become more frequent when followed by reinforcers are called: respondent behaviors. unconditioned responses. associative behaviors. operant behaviors.

The answer is "operant behaviors".

Operant conditioning is a sort of learning where conduct is controlled by outcomes. Basic ideas in this is constructive reinforcement, negative fortification, positive discipline and negative discipline. Through operant conditioning, an affiliation is made between a conduct and a result for that conduct.