...respiration! 
Respiration is the biochemical process in which the cells of an organism obtain energy by combining oxygen and glucose, resulting in the release of carbon dioxide, water, and ATP (the currency of energy in cells). Source: https://study.com/academy/lesson/what-is-respiration-definition-process-equation.html
I hope that helps! :)
 
        
             
        
        
        
<span>The mechanism that affected the gene pool of the immigrants that entered the United States through Ellis Island from 1892 to 1954 is B. gene flow. Gene flow is the transfer of genes or alleles from one population to another. The migration of millions of individuals from countries across the Atlantic Ocean to the United States is responsible for the changes in the gene pool of the immigrants.</span>
        
                    
             
        
        
        
"To help foster peace and economic collaboration among European nations" is the one among the following choices given in the question that <span>best describes the purpose of the European Union. The correct option among all the options that are given in the question is the first option or option "A". </span>