Answer:
B. AgNO₃
Step-by-step explanation:
If the products contain Ag, Cl, K, and NO₃, then this means that these were also the reactants. Remember that matter cannot be created nor destroyed in a chemical reaction, so whatever elements in the reactants were used, would be found in the products. In other words, an element does not change into another.
AgNO₃ + KCl → AgCl + KNO₃