The principle fuel used as a petrol substitute for road transport vehicles is bioethanol. Bioethanol fuel is mainly produced by the sugar fermentation process, although it can also be manufactured by the chemical process of reacting ethylene with steam.
Basically, a plant can be considered as bioethanol becacuse it is a sugar fuel for animals. Animals consume plants for fuel to survive.
 
        
             
        
        
        
Correct Answer is A. They were able to increase their productivity due to the popularity of tractors.
 
        
             
        
        
        
Stimulus is something that causes a psychological response. It can be internal or external. The stimulus is the contact with the hot pan. It is an external stimulus. Sense organs, such as the sensory receptors in the skin are sensitive to external stimulus. The quickly pull of your hand is a reflex action.
The contact causes a nerve impulse that will travel to the spinal cord via the sensory neurons.<span>To respond to the stimulus of the reflex arc, the muscle needs to contract to pull the hand quickly away from the hot pan.</span>
        
                    
             
        
        
        
Answer:
Explanation:
Look I would help but I'm not learning that stuff yet in Middle School.