d'Anconia Copper is an all-equity firm with 60 million shares outstanding, which are currently trading at $20 per share. Last month, d'Anconia announced that it will change its capital structure by issuing $300 million in debt. The $200 million raised by this issue, plus another $200 million in cash that d'Anconia already has, will be used to repurchase existing shares of stock. Assume that capital markets are perfect. At the conclusion of this transaction, the number of shares that d'Anconia Copper will repurchase is closest to:

5 million

15 million

20 million

40 million