In Which of the Following Situations Will a Smaller Sum

In which of the following situations will a smaller sum be unable to discharge a larger debt?

A) If the smaller sum is paid before the due date of the larger debt.
B) If an additional article or service is given together with the payment of the smaller sum.
C) If the smaller sum is paid when the larger sum would ordinarily be due,but the debtor is on the verge of insolvency.
D) A smaller sum is never able to discharge a larger debt.