Answer:
D. number of individuals in a species
 
        
             
        
        
        
Answer:
Dual distribution
Explanation:
Dual distribution is a method of distribution or arrangement, whereby a company uses majorly two approaches simultaneously in distributing their products to their end-users. The company or manufacturer of the product sells their products directly to the end-users and also sells their product to companies that act as marketing intermediaries that later resell their products to the end-users. 
According to the information given in the question above, we can infer that the method of distribution used by pharmaceutical companies is an example of <em>dual distribution.</em>
 
        
             
        
        
        
Founding population arrives, biogeographic isolation occurs, genetic changes