The XYZ Steel Company Produces Its Own Coal for Use

The XYZ Steel Company produces its own coal for use in its production facility.The demand for steel is given by P_s = 500 - 2Q_s and the total cost of producing steel is given by TC_s = 175Q_s,where Q_s is tons of steel per week.The price of coal in a perfectly competitive market outside the firm is $250 per ton,and the total cost of producing coal is given by TC_c = 40 + 5Q_c²,where Q_c is tons of coal per week.How much coal will XYZ sell outside the firm?

A) 6.25 tons.
B) 18.75 tons.
C) 25 tons.
D) 43.75 tons.
E) 75 tons.