（2022 光大）Digital Payments: The Dash from Cash
For the past 3,000 years, when people thought of money they thought of cash. From buying food to settling bar tabs, day-to-day dealings involved creased paper or clinking bits of metal. Over the past decade, however, digital payments have taken off — tapping your plastic on a terminal or swiping your card on a smart phone has become normal. Now this revolution is about to turn cash into an endangered species in some rich economies. That will make the economy more efficient — but it also poses new problems that could hold the transition hostage.
Q: Which of the following is not the form of digital payment?

A Using clinking bits of metal

B Tapping “plastic” on a terminal

C Swiping credit cards

D Using a smart phone