The answer is a low-density particle
        
                    
             
        
        
        
Answer:
B. Local animal populations would start to decrease.
Explanation:
Rabies is a terminal illness, so if an animal gets it, it will most likely die without treatment. This would decrease the population. 
 
        
                    
             
        
        
        
In biological<span> taxonomy, </span>race<span> is an informal rank in the taxonomic hierarchy, below the level of subspecies. ... </span>Races <span>may be genetically distinct phenotypic populations of interbreeding individuals within the same species.
i really hope this helps (:</span>
        
             
        
        
        
I believe that the concept of reaction range proposes that genetics establishes boundaries, whereas environment determines where a person falls within that range. Range of reaction is a concept in psychology, genetics, and related fields that the expressed characteristics or traits of an organism depend on both the genetic characteristics and the environment.
        
             
        
        
        
I believe the anwser you are looking for is the 
Cell Membrane.
It is a substance that lets things in and out of the cell