Why of the following is best sign that cooking pancake batter causes a chemical change?

Please provide me with the options for the best sign that cooking pancake batter causes a chemical change. I need the list of options to determine the best answer.

For example, the options could be:

* A. The batter changes color.

* B. The batter becomes solid.

* C. The batter changes shape.

* D. The batter smells different.

Once you provide the options, I can tell you which one is the best sign of a chemical change and why.