Natural selection a process that occurs over successive generations and is defined as the differential reproduction of genotypes. Natural selection requires heritable variations in a given trait
        
             
        
        
        
Tears and mucous membrane are part of the General defense
system. The General defense system of the body consists of the skin, clotting,
sweat glands, lysozyme, mucous membranes, nasal hairs, cilia, hydrolic acids,
and the vagina. General defense systems have a vital role in giving barriers to
stop bacteria in entering our body which will make us sick.
 
        
             
        
        
        
Answer:
The awnser is c. mucus good luck!
Explanation:
 
        
             
        
        
        
<span>Persentase oksigen di udara di dua mil (3,2 km.) Pada dasarnya sama dengan di permukaan laut (21%). Namun, tekanan udara adalah 30% lebih rendah pada ketinggian yang lebih tinggi karena fakta bahwa atmosfer kurang padat - yaitu, molekul udara yang jauh apart.When kita menghirup udara di permukaan laut, tekanan atmosfer sekitar 14,7 pounds per square inch (1,04 kg. per cm.2)
(i speak indoinision to) 
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