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Well, I think the answer would be, Both biomass and coal energies are inexpensive, but they release greenhouse gases.</span>
        
                    
             
        
        
        
The variable that researchers manipulate is the independent variable.
The reason for this is because in experiments different manipulations are often introduced. The sole purpose of these manipulations is to see whether they will affect our independent variable and if they will change its value. 
        
                    
             
        
        
        
A force that creates something MUST be constructive force so the answer will be B.
        
                    
             
        
        
        
The answer is A. Gravity pulls down on all parts of a plant.
        
             
        
        
        
Answer:
Major types include fats and oils, waxes, phospholipids, and steroids. The three primary types of lipids are phospholipids, sterols, and triglycerides. 
Explanation: