The answer is B Carnivores. This is because they are at the top of the web.
 
        
             
        
        
        
The answer is B. Asteroids
        
             
        
        
        
Answer: What roses are the best flowers is a non-scientific question. 
Explanation: What flower is better is determined by personal opinion. I might think the red roses are prettier and you might think the white ones are. Where all the other questions can be tested all equally and it is not an opinion.
 
        
                    
             
        
        
        
Answer:
The diagram can be improved by:
                                   Lungs
                                        ↓
                                    oxygen
                                        ↓
                       Red blood cells (carrying oxygen)
                                        ↓
                   Organs (like stomach and liver etc) from where carbon     
                                is taken and oxygen is supplied
                                          ↓
                    RBC's carrying Carbon dioxide to the lungs 
The component which is missing in the diagram are the organs where exchange of gases occurs. The red blood cells carry oxygenated blood from the lungs to all parts of the body and carries the wast carbon dioxide gas from them back to the lungs. The carbon dioxide is then exhaled by the lungs.