In which of the following circumstances will payment of a lesser amount fail to discharge a debt, despite a creditor's promise to accept the lesser amount in "full satisfaction" of the debt:

Where the creditor has agreed that the debtor pay the lesser amount on an earlier date.

Where the creditor has agreed that the debtor pay the lesser amount by cheque instead of cash.

Where the creditor has agreed that the debt be paid by a third party.

Where the creditor has agreed that the debtor accompany payment of the lesser amount with some other act they were not originally bound by the contract to perform.