Answer the following question given this paragraph: 

The student athlete in Figure below is practically flying down the track! Running takes a lot of energy. But you don’t have to run a race to use energy. All living things need energy all the time just to stay alive. The energy is produced in chemical reactions. A chemical reaction is a process in which some substances, called reactants, change chemically into different substances, called products. Reactants and products may be elements or compounds.


Q: What is a process where some substances called reactants change chemically into different substances called products?


A:
chemical reaction