Under federal law, only the U.S. Postal Service has the right to deliver first-class mail. Thus, a

Question:

Under federal law, only the U.S. Postal Service has the right to deliver first-class mail. Thus, a consumer can either send a letter via the U.S. Postal Service for less than 50 cents or pay FedEx or UPS $10 or more to deliver it. What is the shape of the demand curve faced by the U.S. Postal Service in the market for first-class mail?