Which One of the Following Is the Equilibrium Expression, K_P $\leftrightarrows$

Which one of the following is the equilibrium expression, K_P, for the reaction that produces lime, CaO, from limestone, CaCO₃? CaCO₃(s) $\leftrightarrows$
CaO(s) + CO₂(g)

A) $\frac { \left[ \mathrm { CaCO } _ { 3 } \right] } { [ \mathrm { CaO } ] \left[ \mathrm { CO } _ { 2 } \right] }$
B) $\frac { 1 } { \mathrm { P } _ { \mathrm { Co } _ { 2 } } }$
C) $\frac { [ \mathrm { CaO } ] \left[ \mathrm { CO } _ { 2 } \right] } { \left[ \mathrm { CaCO } _ { 3 } \right] }$
D) [CaO][CO₂]
E) $\mathrm { P } _ { \mathrm { co } _ { 2 } }$