The most logical contributing factor for the endangered status of black-footed ferret is Human encroachment. Farmers and ranchers (with government assistance) eliminated many prairie dogs because their underground complexes were destructive to fields. This led to decrease in the prairie dog populations, the primary prey of black-footed ferret. 
 
        
                    
             
        
        
        
First,  the yellow fever  virus  is  phagocytosed  by white  blood  cells.   The phagocytosed white  blood  cell  then travel  through  the  lymph  vessel. Since  lymph  node  contain  white blood and   filter  lymph,  the  yellow  fever  phagocytosed  with  white  blood  cell  establish  in  the  lymph  node.
        
                    
             
        
        
        
D because your calf muscle is under your knee in back to if it’s already built up and can go to the heel bone because the calf muscle is connected to the heel bone