a chemical reaction a physical change photosynthesis evaporation
I gave my students this multiple choice question: Hydrochloric acid is added to a beaker containing a piece of zinc. As a result, zinc chloride is formed and hydrogen gas is released. This is an example of

Only one answer is correct among these 4 choices:
- a chemical reaction
- a physical change
- photosynthesis
- evaporation

Could you tell me which one is correct?

a chemical reaction