Read the list of sentences from the article. 1. In a physical change, the material involved is structurally the same before and after the change.

2. A piece of metal may be heated in a fire until it glows, but the metal is the same material before heating and after cooling.

3. Chemical changes require the breaking and forming of chemical bonds during a chemical reaction.

4. The creation of a new, solid substance from two liquid substances indicates that a reaction has taken place that has altered the original substances.

Which two sentences, taken together, provide the BEST evidence to support the idea that both physical and chemical changes can significantly change the appearance of a substance?

a. 1 and 3

b. 1 and 4

c. 2 and 3

d. 2 and 4