Answer:
Genetic variation occurs mainly through DNA mutation, gene flow (movement of genes from one population to another), and sexual reproduction. ... 
Explanation:
Most mutations that result in genetic variation produce traits that confer neither an advantage or disadvantage. Hope that this helps you and have a great day :)
 
        
             
        
        
        
C) carbon dioxide and water is the answer
        
             
        
        
        
Answer:
yes, like poles can attract each other
Explanation:
this is when a magnet is one side north and the other south. They dont attract and repel when it it (north,north) and (south, south)
 
        
             
        
        
        
Air pollution; smoking in the house
        
             
        
        
        
Immune System is the system that consists of proteins and cells.