A. 500,000 indigenous people living in Brazil.
        
             
        
        
        
between Europe and Asia (dividing Eurasia): along the Turkish Straits, the Caucasus and the Urals (historically also north of the Caucasus, along the Kuma–Manych Depression or along the Don River) between Asia and Africa (dividing Afro-Eurasia into Africa and Eurasia): at the Isthmus of Suez.
 
        
                    
             
        
        
        
C, because it is bounded to the west by the Black Sea
        
             
        
        
        
The informal sector lacks land, capital, and technology, and can be less productive than formal enterprises, however, it can improve individual earnings and add money into the economy. It is the access to the market and power to purchase that can assist the productivity of the informal worker. If products can be sold on a cheaper mass scale to informal workers to use as a resource, this could help improve this sector to be more meaningful.