On 1/7/2015 Rojas Company purchased for $560,000 a mine estimated to contain 2 million tons of ore.the company paid for drilling 20,000$ and it expects to pay 20,000 as restoration cost .during 2015 the company extracted 500,000 tons and sold 200,000.the book value of the mine at the end of 2015 will be :

Select one: a. 540,000 b. 450,000 c. 150,000 d. 60,000