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. The reaction function of the remaining T !1 firms is:

A) Q_{T !1} = 50 !2.5Q₁.
B) Q_{T !1} = 50 !0.5Q₁
C) Q_{T !1} = 16 !0.4Q₁
D) Q_{T !1} = 20 !0.5Q₁
E) None of the above.