Answer:
Layer A is the crust and Layer B is the mantle.
 
        
                    
             
        
        
        
 starts with sunlight and photosynthesis if you are talking about plants
 
        
                    
             
        
        
        
Answer:
Less water. 
Explanation:
If the plant is "drought-resistant" then that should mean less water is required for the plant to perform photosynthesis. 
 
        
             
        
        
        
Drag is another one i actually did this project in 5th grade so i know some of this hope this helps.
        
             
        
        
        
Fire can be accidental or intentional, and it can cause erosion.