Consider the following equilibrium reaction.

$$\begin{array}{*{20}{l}} {{\text{2S}}{{\text{O}}_{\text{2}}}{\text{(g)}} + {{\text{O}}_{\text{2}}}{\text{(g)}} \rightleftharpoons {\text{2S}}{{\text{O}}_{\text{3}}}{\text{(g)}}}&{\Delta {H^\Theta } = - 197{\text{ kJ}}} \end{array}$$

Which change in conditions will increase the amount of ${{\text{S}}{{\text{O}}_{\text{3}}}}$ present when equilibrium is re-established?

A.     Decreasing the concentration of ${{\text{S}}{{\text{O}}_{\text{2}}}}$

B.     Increasing the volume

C.     Decreasing the temperature

D.     Adding a catalyst

C