\(\text{CO}_{(g)}\) + \(\frac{1}{2}\)\(\text{O}_2{(g)}\) \(\rightarrow\) \(\text{CO}_2{(g)}\)
\( \Delta n_g = 1 - \left( 1 + \frac{1}{2} \right) = -\frac{1}{2} \)
\( \frac{K_P}{K_C} = (RT)^{\Delta n_g} = \frac{1}{\sqrt{RT}} \)
Thus the correct answer is option 4.