Final answer:
Using the Law of Conservation of Mass, 2 grams of reactant were consumed to produce 2 grams of product, making option (b) correct.
Step-by-step explanation:
To determine how many grams of reactant were consumed to produce 2 grams of product, we must apply the Law of Conservation of Mass. This law states that mass is neither created nor destroyed in a chemical reaction. Given the example where 2 grams of substance A react with 16 grams of substance B to produce 18 grams of substance C, the combined mass of the reactants will be equal to the mass of the product formed.
If we have 2 grams of the product, we can infer that the same amount of mass in reactants was consumed. Therefore, the answer to the question is that 2 grams of reactant were consumed to produce 2 grams of product, making (b) the correct option. Note that this assumes a one-to-one conversion without excess reactant, which is suggested by the information provided.