Answer:
interleukin-2 (IL-2) is an interleukin, a type of cytokine signaling molecule in the immune system. It is a 15.5–16 kDa protein[5] that regulates the activities of white blood cells (leukocytes, often lymphocytes) that are responsible for immunity. IL-2 is part of the body's natural response to microbial infection, and in discriminating between foreign ("non-self") and "self". IL-2 mediates its effects by binding to IL-2 receptors, which are expressed by lymphocytes. The major sources of IL-2 are activated CD4+ T cells and activated CD8+ T cells
Explanation:
 
        
                    
             
        
        
        
Gaseous atoms and plasmic ions expand in all directions.
 
        
                    
             
        
        
        
Answer:
C)	text-to-world  
Explanation:
Kyle makes a text-to-world connection between the story that is set in London and his brother's real life experiences. Text-to-world connections remind you of an experience that someone else has had.
 
        
             
        
        
        
Answer: The current predicted doubling time is 61years which makes 50years in your option the nearest possible answer.
Explanation:The world's current (overall as well as natural) growth rate is about 1.14%, representing a doubling time of 61 years. 
We can expect the world's population of 6.5 billion to become 13 billion by 2067 if current growth continues.