[单选题]
Given the following information:vn 3gh6n en 8jfig m1dkseatr9 0g;l819 a1y.ybkl ly2h*,/kiyc d6q/ C(s)+$O_2$(g)→$CO_2$(g); ΔH= -393.5kJ mol$^{-1}$
CO(g)+$\frac{1}{2}$$O_2$(g)→$CO_2$(g);ΔH= -283.0kJ mol$^{-1}$
The standard enthalpy of formation of carbon monoxide (CO) is:
A. +110.5kJ mol$^{-1}$
B. -676.5kJ mol$^{-1}$
C. +676.5kJ mol$^{-1}$
D. -110.5kJ mol$^{-1}$