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 should XYZ steel charge itself for coal?

A) $250 per ton.
B) $350 per ton.
C) $500 per ton.
D) $750 per ton.
E) $1,000 per ton.