Meiosis. Sexual recombination. Crossing over. Independent assortment. Mutations.
The two MAIN sources would be genetic(sexual) recombination and mutations. Mutations allow for genetic variation, while genetic recombination allows for genetic shuffling. :)
        
             
        
        
        
A means of water erosion would not be C. natural water springs. Erosion occurs when water or wind removes rock, dissolved material, and soil from one location to another. All the other options describe water moving from one location to another, which accurately describes what erosion does. 
        
             
        
        
        
An antimicrobial<span> is an agent that kills microorganisms or inhibits their growth. </span>Antimicrobial <span>medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria and antifungals are used against fungi.
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Selective toxicity<span> refers to the ability of the drug to targets sites that are relative specific to the microorganism responsible for infection. Sometimes these sites are unique to the microorganism or simply more essential to survival of the microorganism than to the host.
Selective theory relates to antimicrobial because the antimicrobial is the drug that kills microorganisms and inhibits there growth,  selective theory is the ability of the drug.
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Hello!
The term that describes the amount of water vapor in the air is absolute humidity.