Answer: A,B and C
Explanation
        
             
        
        
        
The belt between Mars and Jupiter is mad of space rocks known as astroids. Hope that helps!
        
             
        
        
        
Answer:
The alveolar walls and capillary walls share a membrane. That's how close they're getting. This allows oxygen and carbon dioxide to readily pass from the respiratory system to the circulation. Oxygen molecules bind to red blood cells as they return to the heart.
 
        
             
        
        
        
A dense growth of plant life in a aquatic ecosystem which many animals living there die(due to lack of enough oxygen present in water) and the ecosystem gets completely disrupted. 
Eutrophication excessive richness of nutrients in a lake or other body of water, frequently due to run-off from the land, which causes a dense growth of plant life.