Some students decided to do an experiment with water and an antiacid tablet to show how the law of conservation of matter worked in a chemical reaction. They placed the beaker of water and the tablet on the scale and recorded a measurement of 250 g. The students then placed the tablet in the water and waited for the reaction to stop. Once all of the fizzing stopped, they recorded the final mass. They found that the reading on the scale was 225 g. Which answer below best explains why the mass was not conserved during this experiment?

a. Mass is always conserved, so their scale must be broken.

b. The students must not have put all of the antiacid tablet in the water.

c. When the water and antiacid tablet reacted with one another, the matter compressed together and the mass decreased.

d. The chemical reaction produced a gas that they could not see which escaped from the open beaker, which caused the mass to decrease.