Solids ${\mathrm{CaCO}}_3$ and CaO and gaseous ${\mathrm{CO}}_2$ are placed in a vessel and allowed to reach equilibrium

$\mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)\rightleftharpoons {\mathrm{CaCO}}_3\left(\mathrm{s}\right)+180\mathrm{kJ}$

The quantity of $\mathrm{CaO}$ in the box could be increased by

Le Chatelier's principle states that if the forward reaction producing the products is endothermic, lowering the temperature will increase the relative amount of reactants while favoring the yield.

$\mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)\rightleftharpoons {\mathrm{CaCO}}_3\left(\mathrm{s}\right)+180\mathrm{kJ}$

Being endothermic, a rise in temperature will cause the reaction to shift to the right and produce more energy.

Hence option B is correct