Nature does = environmental stress or changes
        
             
        
        
        
The wording of this is confusing. I think it’s A and B and I’m hesitant say that it’s also C but only if you know the mutation and the gene. 
Also for A you would only know a partial sequence of the gene.
        
             
        
        
        
Answer: The more rainfall, the bigger the tree, so that creates a rainfall
Explanation:
 
        
             
        
        
        
Answer: Decomposer
Explanation:
Bacteria feed on the dead and decaying organism, in which they feed on them and obtain energy from them.
It is not a mutual relation because the host cell on which they feed is not alive. They eat the organic matter that is present in environment.
The bacteria and fungi clean the environment in this way. The dead plants and animals are decomposed in the environment and the nutrients get back  into the soil.
hence, the correct answer is option B