Which Among the Situations Below States a Correct Principle of Law

Which among the situations below states a correct principle of law?

A) Third Person pays Debtor's debt without intending to be reimbursed by Debtor. The payment will not extinguish the obligation even if accepted by Creditor if Debtor does not consent to the payment.
B) Third person pays Debtor's debt without intending to be reimbursed by (c) Debtor. The payment will extinguish the obligation if Debtor does not consent to the payment.
C) Debtor is obliged to give Creditor a Rado watch. Since no Rado watch was available on the due date, Debtor decided to deliver a watch of a different brand more valuable than the one that is due. Creditor must accept the watch.
D) D owes C ₱20, 000. D pays B, brother of C. The payment is not valid even if it redounded to the benefit of C.