Answer: a.  water cycle
Explanation:
A water cycle can be define as the cycle of water in which water in various states like solid, liquid and gaseous forms circulates in different spheres of the earth. It describes how water evaporates from the surface of earth, the water vapors accumulate in the atmosphere, these water vapors become cool and condense in the form of rain or other kind of precipitations. The water cycle plays an important role in changing the weather condition of a region. 
 
        
                    
             
        
        
        
Answer:
in some cases this is true a compound is a mixture of elements although it is actualy false the diffrence is actualy baced on what elements it is made of like sulfur Dioxide is when sulfur reacts with the contents of the air when burning and reacting but they arnt always diffrent most caces it is just what element you use. 
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Answer:
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