You must adopt a payment policy that protects the Government against fraud. Acceptable payments include, but are not limited to, the following:

(a) U.S. currency or any form of credit instrument made payable on demand in U.S. currency, e.g., cashier's check, money order. Promissory notes and postdated credit instruments are not acceptable.

(b) Irrevocable commercial letters of credit issued by a United States bank payable to the Treasurer of the United States or to the Government agency conducting the sale.

(c) Credit or debit cards.