Antisocial behavior is characterized by a disregard for the rights of others and often involves actions that harm or lack consideration for the well-being of others.

Antisocial behavior is characterized by a disregard for the rights of others and often involves actions that harm or lack consideration for the well-being of others.

Let's evaluate each statement:

• I - bad parenting: Inconsistent discipline, lack of supervision, or neglectful/abusive parenting can contribute to the development of antisocial behavior.
• II - peer influence: Association with peers who engage in delinquent or antisocial activities can strongly influence an individual to adopt similar behaviors.
• III - dealing in hard drugs: Engaging in illegal activities like drug dealing is a form of antisocial behavior itself, and the lifestyle associated with it often involves other antisocial acts.
• IV - good parental care: Good parental care, which includes supportive relationships, clear boundaries, and positive role modeling, is generally associated with reducing the likelihood of antisocial behavior, not causing it.

Therefore, bad parenting, peer influence, and dealing in hard drugs are all potential causes or contributing factors to antisocial behavior. Good parental care is not.

The correct option must include I, II, and III, and exclude IV.

The final answer is $\boxed{\text{C. I, II and III only}}$.