Final answer:
The definitive characteristic common to all chemical changes is the production of a new substance as a result of a chemical reaction.
Step-by-step explanation:
What is common to all chemical changes? The characteristic common to all chemical changes is that a new substance is produced. During a chemical change, the chemical bonds of the substances break, and the atoms rearrange themselves into new substances with new chemical bonds. This process is known as a chemical reaction.
While a change of state, color change, or heat release can accompany chemical changes, they are not universal to all chemical reactions. For example, not every chemical change results in a temperature change or heat being released. However, the production of a new substance with different chemical properties is a definitive marker of a chemical change.
Therefore, the correct answer to the student's question is: c) A new substance is produced.