In the system ${\mathrm{CaCO}}_3\left(\mathrm{s}\right)\rightleftharpoons \mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$, doubling the mass of CaO will cause the equilibrium concentration of CO₂ to 

• A

  become half of its initial value

• B

  remain unchanged 

• C

  become twice its initial value

• D

  a value which cannot be predicted unless K_c is known