已知反应B4C(s)()+4O2(g)()=2B2O3(s)()+CO2(g)的ΔrHmΘ=-2859()kJ·mol-1；而且ΔfHmΘ(B2O3)()=()-1273()kJ·mol-1；ΔfHmΘ(CO2)()=()-393()kJ·mol-1。则ΔfHmΘ(B4C)为()。A.()-()2859()kJ·mol()-()1B.()-()1666()kJ·mol()-()1C.()1666()kJ·mol()-()1D.()-()80.0()kJ·mol()-()1