The metals producer Soci-Etain has acquired rights to a deposit of tin in Ecuador. According to the company geologists, there are 20,000 units of tin in the deposit. The estimate of the cost of extraction and smelting of the tin in each period is C(Y,) =25x Y, +0.005x Y, , where Yt represents number of units of tin extracted/smelted in period 't = 0, 1, 2..." The world market price of a unit of tin is $100. This is not expected to change for at least five years. The return (proxy for interest rate) that Soci-Etain can earn on its other assets around the world is 4%. 18. If Soci-Etain has only a two-rear lease on the deposit in Peru, how much of the tin will it abandon at the end of the lease? A. None of the tin will be abandoned, all will be extracted B. Some of the tin, but fewer than 2,000 units will be abandoned C. At least 2,000 units but fewer than 4,000 units will be abandoned D. At least 4,000 units but fewer than 6,000 units will be abandoned E. At least 6,000 units (6,000 or more) will be abandoned