An only son ower $20,000$ Euros to his father for a loan that the latter made to him some years ago. When the father dies and the son inherits all his assets, is the obligation to pay the loan estinguished?

a$)$ Yes, by offhetting debts between the two.

b$)$ Yes, by confusion of rights between creditor and debtor.

e$)$ No$,$ because the father has not written off the debt.

d$)$ No$,$ because the father has not expressly consented to it$.$