contribution is the answer 
 
        
                    
             
        
        
        
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Answer:
A blue moon is an additional full moon that appears in a subdivision of a year: either the third of four full moons in a season, or a second full moon in a month of the common calendar
Explanation:
The Moon can turn blue when there’s a certain amount of dust or pollution in the air. The extra dust scatters blue light, making the Moon appear more blue. 
 
        
             
        
        
        
The impact of invasive species is that it may cause environmental harm, economic harm, or impact human health.
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I chose the answer that said "Transition to socialist and communist government systems, and creation of labor unions."