Answer:
me no speak spanish only Ghetto English....a keke 
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Biological communities evolve through ecological succession. Ecological succession is the change in the structure and composition of species in a specific ecological community over time that can be observed. Ecological succession can occur as a natural process of time, or it can be instigated by a sudden event, a wild fire, for example. There are natural changes that occur that effect the species type and variation that exists and thrive in the communities.
        
                    
             
        
        
        
Answer:
Without an oxygen atmosphere very few things could live on the early Earth. Anaerobic bacteria were probably the first living things on Earth. The early Earth had no oceans and was frequently hit with meteorites and asteroids.
Explanation:
 
        
             
        
        
        
Its C. Whenever you perform an experiment you want to make sure its as controled as it can possibly be.