In the heterogenous equilibrium $CaCO_3 (s) \rightleftharpoons CacO_3 +CO_2 (g)$ What would be the effect of addition of $CaCO_3$ on the equilibrium concentration of $CO_2$?

Question

$\begin{array}{1 1} \text{Increases} \\ \text{Unpredictable} \\ \text{Decreases} \\\text{Remains\;unaffected} \end{array}$