After mining 9,273 tons of coal, Blue Sky Mining's managers note that the marginal cost of mining the next ton of coal would be $\$ 40$ per ton. They also calculate that the user cost of mining that next ton of coal would be $\$ 35 .$ If the market price of coal is $\$ 72,$ should Blue Sky mine an additional ton of coal?
a. Yes.
b. No.
c. More information is needed.