How would you prepare the following substances by a precipitation reaction? ZnCrO₄ + ZnS(s) → K₂CrO₄(aq)?

a. ZnO(s)+H₂CrO₄(aq)→ZnCrO₄(s)+2H₂O(l)
b. Zn(NO₃)₂(aq)+Na₂CrO₄(aq)→ZnCrO₄(s)+2NaNO₃(aq)
c. ZnS(s)+K₂CrO₄(aq)→ZnCrO₄(s)+K₂S(aq)
d. ZnCl₂(aq)+PbCrO₄(s)→ZnCrO₄(s)+PbCl₂(aq)