Write a balanced net ionic equation for the reaction of aqueous solutions of cadmium(II) chloride and sodium sulfide.
a) CdCl₂ + Na₂S → CdS + 2NaCl
b) CdCₗ2 + Na₂S → CdS + NaCl
c) CdCl₂ + Na₂S → CdS + Na₂Cl₂
d) CdCl₂ + 2Na₂S → CdS + 2NaCl