Tropopause is the boundary between the troposphere and stratosphere.
Explanation:
- Tropopause marks the transition region between troposphere and stratosphere.
- As we move up from the Earths surface , the temperature gets colder but when we reach the tropopause the temperature becomes constant and the temperature does not fall further.
- It is at a height of about 9Km at the polar region while at a height of 17 Km at the equitorial region.
 
        
             
        
        
        
The position of the diver is described as "below a certain point"; therefore, the reference point must be above the diver. For a diver in the middle of his dive, the bottom of the pool, the other swimmers and the far side of the swimming pool are likely to be below the diver, or at level with the diver at most. Out of the options, the only point of reference that is likely to be above the diver is B. the diving board. 
        
             
        
        
        
Oxygen, sulfur, nitrogen, and hydrogen!
        
                    
             
        
        
        
Answer:
way of seeling and product that he/ she is seeling