Answer: It  would us  valine 
Explanation:
 
        
             
        
        
        
Natrual variations i think 
        
                    
             
        
        
        
Answer:
Scientist study moving forces, biology, chemistry, and any other natural or unnatural study.
 
        
             
        
        
        
Answer:
tagging the sharks
Explanation:
To learn their behavioral patterns researchers are tagging the sharks. Doing so allows the researchers to track their movements individually and gather data as to how they move, where they migrate to, how many migrate together, etc. All this information is extremely valuable and when pieced together can shed light on why they have certain behavioral patterns or traits.