Answer:
I would say both the Oracle and Creon cause Oedipus to do the most harm
Explanation:
I say this because if the Oracle hadn't told the king that he would be murdered by his son or that his son will marry his mother or if he had told the king how to prevent this the king wouldn't have tried to kill Oedipus as a baby Oedipus been raised by the king and queen he wouldn't have been traveling down that road and killed the King and he wouldn't have landed back in his hometown and married his mother reason being he would have already known that was his mother and that was his father and he'd have no reason to want to do that but as he grew up outside of that family he did not know dot-dot worth his biological parents causing him not to care and after he had found out the damage had already been done you can also write this as it's just the father's fault
