7. You are operating a coal strip mine. The mine can produce 150,000 tons a year and to close the mine will cost $5 million. When should the mine be closed?

A) At a net coal price after extraction costs of $33.33 per ton.

B) At a net coal price after extraction costs greater than $33.00 per ton.

C) If the mineable coal still exists it should never be closed.

D) If mineable coal still exists at a net coal price significantly below $33.33 if coal prices have high volatility.

E) None of the above.