What do these two changes have in common?
photosynthesis
cooking an egg

 - Both are only physical changes.
 - Both are chemical changes.
 - Both are caused by cooling.
 - Both are caused by heating.
Step 1: Think about each change.
Photosynthesis is a chemical change. Plants make sugar using carbon dioxide, water, and energy from sunlight.
Cooking an egg is a chemical change. The heat causes the matter in the egg to change. Cooked egg and raw egg are different types of matter.
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.
Cooking is caused by heating. But photosynthesis is not.
Both are caused by cooling.
Neither change is caused by cooling.