What do these two changes have in common?
sauce burning on a stove
a crayon melting in the sun

 - Both are only physical changes.
 - Both are caused by cooling.
 - Both are caused by heating.
 - Both are chemical changes.
Step 1: Think about each change.
Sauce burning on a stove is a chemical change. High temperatures case the sauce to react with oxygen in the air. The sauce turns black and no longer tastes good.
A crayon melting in the sun is a change of state. So, it is a physical change. The crayon changes state from solid to liquid. The crayon is still made of wax, even after it melts.
Step 2: Look at each answer choice.
Both are only physical changes.
A crayon melting in the sun is a physical change. But sauce burning is not.
Both are chemical changes.
Sauce burning is a chemical change. But a crayon melting is not.
Both are caused by heating.
Both changes are caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.