Answer the following question given this paragraph: 

Did you ever wonder what happens to a candle when it burns? A candle burning is a chemical change in matter. In a chemical change, one type of matter changes into a different type of matter, with different chemical properties. Chemical changes occur because of chemical reactions. You can see more examples of chemical changes at this URL: http://www. youtube. com/watch?v=66kuhJkQCVM .


Q: Chemical changes occur because of what?

 Choices:

- liquid reactions

- evaporation

- toxic reactions

- chemical reactions

A:
chemical reactions
