Recall that your business provides CDs that complement the teaching provided by your employees in Mexico. Assume that you decide to capitalize on these CDs by selling them to a large retail store based in Mexico. The CDs are less effective without the teaching, but still can be useful to individuals who want to learn the basics of the English language. You do not want to take the risk of sending a case of CDs to the retail store unless you can be sure of receiving payment. Explain how you can ensure payment for the CDs.