The correct answer among all the other choices is D. The sentence is correct as it is written. The sentence doesn't need to be revised. Thank you for posting your question. I hope this answer helped you. Let me know if you need more help. 
        
             
        
        
        
Answer:
It would be the sun! aka b
Explanation:
Energy from the sun and the force of gravity drive the continual cycling of water among these reservoirs. As the water is heated, it changes state from a liquid to a gas. This process is called evaporation. As more energy is added to the water, the water molecules move faster and farther apart.