Final answer:
According to the Law of Conservation of Mass, the total mass of the reactants in a chemical reaction that produces 43g of products must also be 43g.
Step-by-step explanation:
If a chemical reaction produces 43g of products, the total mass of the reactants must have been 43g as well, according to the Law of Conservation of Mass. This law states that mass is neither created nor destroyed in a chemical reaction. Thus, the mass of the products must equal the mass of the reactants. Therefore, the correct answer to the given problem is (a) 43 g.