C) hope this helps may not be right :4
        
                    
             
        
        
        
They are variables that cannot be changed or are purposefully not changed in an experiment.
        
             
        
        
        
The radius is on the outside, or lateral side, of the elbow. It connects to the thumb side of the wrist. The radius is bigger and longer than the ulna which is on the inside, or medial side, of the forearm closest to the body.