I believe it’s perpendicular but let me know if I’m wrong:)
        
             
        
        
        
I believe that the instrument Shakira brought back into the mainstream with her hit Whenever, Wherever are the panpipes.
That instrument is a type of a flute consisting of numerous pipes which produce sound when blown into. The name comes from Greek mythology, where the Greek god Pan is often depicted using that instrument. Other than the panpipes, she also used the charango, which is a type of a lute. 
        
             
        
        
        
<span>(a) stability of elements on either side of an imaginary vertical line 
(b) recognizable arrangement of elements based of their proportions 
(c) systematic arrangement of elements based on their size.</span><span />
        
                    
             
        
        
        
I believe the answer is depth!