The carrying capacity of the environment has remained constant.
Hope this helps!
-Payshence xoxo
        
             
        
        
        
<span>Controlled variable is a variable that was made constant in the research. That was because the controlled variables can influence the dependent or independent variable. If the variables is not made constant, it can alter the research result and made it invalid.
In this case, </span>the caffeine and alcohol intake might alter the physical activity or the blood glucose so it should be controlled.
        
             
        
        
        
D or aka changes in the moons orbit
Hope this helps you 
 
        
             
        
        
        
The best answer among the choices given is option D. Both growth and reproduction is the <span>characteristic of living things that is important to the survival of a group of animals rather than an individual member of this group. These two are very important in order for the survival of all the living things on Earth. Without these things, life here on Earth will end.</span>