10. Pharmaceutical companies are offering free one-week or even one-month supplies of drugs to treat everything from diabetes to acid reflux. They hope to get patients to persuade their doctors to prescribe a new therapy or let them switch from an old drug. The drug makers are sending the coupons through the mail and in e-mails, and printing them in newspapers and magazines. From the actions that drug companies take, what can you deduce about the market structure? Is it a perfectly competitive market, monopoly, or what? How do you know?