You are presented with the question "Unequal heating of the Earth's surface by the Sun causes ocean circulation and what?" and the following answer choices: 
- Energy.
 - climate
 - raincoats
 - The atmosphere
 - tropical wind
 - freezing rain
 - pouring down
 - to move people

Now knowing that unequal heating of Earth 's surface by the Sun causes global wind patterns and finally, the pattern of tropical wind and ocean circulation is a key element of global circulation, choose the best answer.


 

     tropical wind    