How would different approaches to therapy attack the following situations?

SCENARIO #1:

A mother brings her young son (eight years old) to the therapist because he is “acting up” in school and at home.  He is extremely hostile and belligerent toward both his teacher and his mother and refuses to cooperate even under threat of punishment.

SCENARIO #2:

A man in his mid-thirties finds that he is having difficulty establishing an intimate relationship with the woman he is dating.  He cares for her and would someday like to get married, but he is reluctant to make a commitment.

SCENARIO #3:

A twenty-five-year-old woman, a high-powered stock broker, is frustrated by her inability to quit smoking.  She has tried several times and has been successful for brief periods, but she always starts smoking again when her life becomes stressful.