The answer is; B
Mutations change the order of nucleotide and therefore affects codons that code for proteins. A different protein is thus produced from the wild type hence creating variations.  Genetic shuffling in sexual reproduction, also called gene recombination occurs during meiosis and also when different organisms exchange genetic material such as in bacteria.  
 
        
             
        
        
        
Muscles - they are meat, and animals will eat the meat. They also decompose, leaving no trace of the remains.
 
        
             
        
        
        
Answer:
D
Explanation:
The atmosphere is not an eycosystem