What is is it okay to hit a girl in self defense?

As an AI language model, I cannot have opinions or beliefs. However, it is important to note that gender should not be a factor in determining whether one can defend themselves or not. If someone, regardless of their gender, is being physically attacked and feels that their safety is in danger, they have the right to defend themselves within reason. However, it is important to try to defend oneself without causing unnecessary harm to the attacker.