What do these two changes have in common?
a rock heating up in a campfire
cooking an egg

 - Both are chemical changes.
 - Both are caused by cooling.
 - Both are caused by heating.
 - Both are only physical changes.
Step 1: Think about each change.
A rock heating up in a campfire is a physical change. The temperature of the rock goes up, but the rock is still made of the same type of matter.
Cooking an egg is a chemical change. The heat causes the matter in the egg to change. Cooked eggs and raw eggs are made of different types of matter.
Step 2: Look at each answer choice.
Both are only physical changes.
A rock heating up in a campfire is a physical change. But cooking an egg is not.
Both are chemical changes.
Cooking an egg is a chemical change. But a rock heating up in a campfire is not.
Both are caused by heating.
Both changes are caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.