Answer:
![\Large \boxed{\mathrm{B. \ a \ chemical \ change}}](https://img.qammunity.org/2020/formulas/chemistry/middle-school/d02kia3cxbpmagtotsi9rswnspt388v39k.png)
Step-by-step explanation:
A chemical change always produces one or more new substances that differs from the initial matter before the change.
The products and reactants both, of a chemical change, can be one or more substances before the change and after the change.