Pretty sure the answer would be C, because you need the warm and cold air to mix.
        
             
        
        
        
Answer:
A cell is the smallest unit of a living thing.
 
        
                    
             
        
        
        
"Crepuscular" means active at dawn and dusk, so if you wanted to avoid coming across the Gila monster when hiking in Arizona you would want to avoid dawn and dusk. 
        
                    
             
        
        
        
Answer:
C, both a and b
Explanation:
Momentum is something you gain, meaning it can be transferred from one object to another. When you slow down, that is your momentum being lost, meaning both and and b are correct