Explanation:

- Option 1: Is binding on the son

In Hanafi law, a contract of dower entered into by a father on behalf of his minor son is binding on the son. This is because the father acts as the guardian and can enter into such contracts considering the son's benefit.

- Option 2: The father is not personally liable for the mahr

While the father can negotiate the mahr, he isn't personally liable for it. It's the obligation of the son once he reaches maturity.

- Option 3: Both (a) and (b)

This option acknowledges both the binding nature of the contract on the son and the lack of personal liability for the father.

Correct Answer

- Option 4: Is neither binding on the son nor the father is personally liable for the mahr

This option doesn't reflect the Hanafi law accurately as fathers can bind their sons in such contracts.