The Demand for the Output of a Multi-Firm Industry Is

The demand for the output of a multi-firm industry is Q_T = 50 !2.5P. The total cost of production of an individual profit-maximizing firm in this industry is TC₁= 4Q₁. If this industry is comprised of 4 firms, firm 1's profit is about:

A) $60.
B) $80.
C) $100.
D) $120.
E) None of the above is correct.