Give the chemical formulas for each of the following compounds in the reaction that occurs when ammonium chloride reacts with barium nitrate to produce solid barium chloride and ammonium nitrate.
a. NH₄Cl and Ba(NO₃)₂
b. BaCl₂ and NH₄NO₃
c. BaCl₂ and Ba(NO₃)₂
d. NH₄Cl and NH₄NO₃