In a popular demonstration, vinegar and baking soda are combined in a bottle as shown. Sodium carbonate, water as well as carbon dioxide gas are formed. The balloon traps the carbon dioxide.

According to the law of conservation of mass, the total mass of the reactants equals the total mass of the products. How could you alter the demonstration above so that the mass of products would not equal the total mass of the reactants?
A) Use less of the reactants.
B) Do not use a clean bottle.
C) Take the balloon off the bottle.
D) Shake the bottle while the chemicals are reacting.