An adolescent client with an antisocial personality disorder has been admitted to the hospital because of drug abuse and repeated sexual acting-out behavior. which client behavior supports the nurse's conclusion that actions directed toward modifying the behavior of this client have been successful?

The correct answer is "identifies the feelings underlying the acting-out behaviour ".
This statement shows that the adolescent is recognizing the feelings and is ready to talk about them. This willingness to express this indicates the development of insight and the sincere need to investigate the true source of these behaviours.
By stating that he will never behave like that again and that he will conform to society's norms, he is simply using expressions with no meaning to him. If he discusses seducing other adolescents, he is just manifesting the behaviour that led him to the hospital in the first place.