Answer:
In this, the controlled variables are stirring and type of sugar. As more stirring might elevate the amount of sugar that dissolves, and different kind of sugars might dissolve in distinct concentrations. So, in order to make sure a fair test, there is a need to keep these variables similar for each cup of water.
Explanation:
 
        
             
        
        
        
All of them are <span>Levels of Organization of Living Things
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That would be false. A catacomb is an ancient underground cemetery.
exact meaning: an underground cemetery consisting of a subterranean gallery with recesses for tombs, as constructed by the ancient Romans.
        
             
        
        
        
I think the answer is ATP
        
                    
             
        
        
        
Earthworms maintain homeostasis by having a dual circulatory system, which contains the closed circulatory system and the coelomic fluid for respiratory gases, food and waste.