Answer:
Burning coal  
Explanation:
The emissions of carbon dioxide would reduce because then they will consume less gasoline. Instead of coal burning, this would reduce the overall concentrations of greenhouse gas emissions and generate energy from wind.
 
        
             
        
        
        
The digestive system enlists the aid of the cardiovascular system and the nervous system. Blood vessels of the digestive system widen to transport more blood.
 
        
             
        
        
        
Answer:
Sure grass.  And there is a lot of grass. Compete with wild horses, wild pigs, wild goats, wild "golfer's who are way off the fairway. Wild deer are in the forests, wild goats in the hills so buffalo and horses manage the plains and the back nine.  So much grass there was no competition...with the wild rabbits.  Grass continues to grow.  The buffalo move to greener pastures once they mowed down the other fields.  When there were Millions of them, they were not starving.
Explanation: Got this from somewhere hoping it helps!