下列反应中表达式正确的是( )。（单选）—5分
A Na(s)+1/2 Cl2 (g) = NaCl(s) ΔrHmθ＝ΔfHmθ(NaCl，s)
B C(石墨) + H2(g) = 1/2 C2H4(g) ΔrHmθ＝ΔfHmθ (C2H4，g)
C CO(g)+ 1/2 O2(g) = CO2(g) ΔrHmθ＝ΔfHmθ (CO2，g)
D CH3OH(g) + O2(g) = CO (g) + 2H2O(g) ΔrHmθ=ΔcHmθ(CH3OH，g)