Which best describes why a chemical change is different than a physical change?

a. a chemical change results in a different state of matter, and a physical change results in a new substance being formed.

b. a chemical change is used to identify characteristics of a substance, and a physical change identifies the behavior of a substance when in a reaction.

c. a chemical change results in a new substance being formed, whereas a physical change will result in a different state of matter.

d. a chemical change is used by scientists to create new substances, and a physical change happens naturally.