Many firms now use e-mail and the Internet to promote their products instead of sending promotional literature to current and prospective customers through the mail. UPS and FedEx continue to grow, offering both overnight and ground package delivery services. As a result, the U.S. Postal Service (USPS) has lost millions of customers and billions in revenue. The USPS has challenges ahead in coping with ________ forces in the marketplace.
A) technological
B) legal
C) social
D) economic
E) competitive