They are called
a. sunspots
        
                    
             
        
        
        
Ethanol is a biofuel, which can <span>be fermented from various sources, but in United States, most of Ethanol is made from "Corn"
In short, Your Answer would be Option A
Hope this helps!</span>
        
                    
             
        
        
        
Answer:
The cells present in the stem are part of the xylem and phloem conductive tissues. They are characterized by being elongated and in tubular form because they transport the substances, the xylem transports  water and  inorganic mineral sales that the root absorbs from the soil. The phloem is responsible for transporting substances synthesized in photosynthesis.
Its tubular and elongated shape facilitates the transport of these substances
 
        
             
        
        
        
Answer:
A closed system is a physical system that does not allow transfer of matter in or out of the system, though, in different contexts, such as physics, chemistry or engineering, the transfer of energy is or is not allowed.
 
        
             
        
        
        
Its is to remove liquid waste from the blood in the form of urine, and keep a stable balance of salts and other substances in the blood and produce erythropoietin, hormone that is the formation of ref blood cells. The kidney remove ursa from the blood through this filtering units called nephrons