The correct response that demonstrates the law of conservation of matter as shown in the balanced equation \( \text{CH}_4 + 2 \text{O}_2 \rightarrow \text{CO}_2 + 2 \text{H}_2\text{O} \) is:
The number of atoms, type of elements, and mass of reactants and products are equal.
This is because the balanced equation shows that the total number of each type of atom (carbon, hydrogen, and oxygen) is the same on both sides of the equation, which aligns with the law of conservation of matter.