Answer:
<u><em>Some cartilage becomes bone through ossification during childhood development. </em></u>
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Explanation:
You forgot to include options. 
 
        
             
        
        
        
Answer:
The freshwater trout requires a lower salt ions to function.
Explanation:
 
        
             
        
        
        
I believe it’s A. On the inside of a person’s body.
        
             
        
        
        
Answer:
Net Primary productivity
Explanation:
In an ecosystem, primary productivity is a term used for autotrophic organisms. It is the process by which these organisms like plants, green algae etc. make their own food using inorganic sources. However, they do not utilize all the matter they make from this process. 
The NET PRIMARY PRODUCTIVITY (NPP) is the amount of organic material that is available for transfer to the next trophic level after subtracting material used for respiration. This means that NPP is the amount available after removal of the one to be lost via respiration i.e. NPP = GPP - respiration.