What do these two changes have in common?
a slice of banana turning brown
burning a marshmallow over a campfire

 - Both are caused by cooling.
 - Both are only physical changes.
 - Both are caused by heating.
 - Both are chemical changes.
Step 1: Think about each change.
A slice of banana turning brown is a chemical change. The part of the banana in contact with the air reacts with oxygen and turns into a different type of matter.
Burning a marshmallow is a chemical change. The heat from the fire causes the type of matter in the marshmallow to change. The marshmallow becomes black and crispy.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Burning is caused by heating. But a slice of banana turning brown is not.
Both are caused by cooling.
Neither change is caused by cooling.