Answer:
While researchers have discovered that there are an excessive number of receptor sites for dopamine, it is not the only neurotransmitter involved in schizophrenia.
Explanation:
 
        
             
        
        
        
I believe it is 'white fur' because living in the Tundra means it is snowing. Snow is white, so basically, the white fur is specifically for the Tundra.
I hope it helps.
 
        
             
        
        
        
It is called  a population since they are all the same species 
        
                    
             
        
        
        
<span>The best and most correct answer among the choices provided by the question is the first choice. One can adapt to the sunny environment by wearing sunglasses. I hope my answer has come to your help. God bless and have a nice day ahead!</span>