Answer:
Effective food supply was most likely an effect on society that resulted from improvements in blood handling during World War I and World War II.
Explanation:
 
        
             
        
        
        
The answer is glucose.
Hope this helps.
        
             
        
        
        
The independent variable is the one that can be changed
I think the correct answer would be water temperature because on the table, the water temperature is increasing by 10 each time so it is changing. 
hope I'm right and hope I helped :)
        
             
        
        
        
The cell membrane allows this to be true