Cherokee Trail of Tears
probably 
        
                    
             
        
        
        
Answer: B
Explanation: Stem cells are the building blocks of the human body. At the start of life, they divide over and over again to create a full person from an embryo. As we age, they replenish cells in our blood, bone, skin and organs. Stem cells could be powerful tools in treating injury and illness.
 
        
                    
             
        
        
        
The USA didn't want communism to spread.
        
             
        
        
        
I think the 3rd answer is correct