Answer:
I thinks is pollution
Explanation:
its the only one that makes sense
 
        
                    
             
        
        
        
Mitosis and cytokinesis. In eukaryotes the processes of DNA replication and cell division occur<span> at different times of the </span>cell division<span> cycle. During </span>cell division<span>, DNA condenses to form short, tightly coiled, rodlike chromosomes. Each chromosome then splits longitudinally, forming two identical chromatids.
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Carbon (C) is an element
Carbon Dioxide (CO2) is a compound
Hydrogen (H) is an element
Sodium Chloride (NaCl) is a compound
A good way to tell whether something is a compound or an element, is that in a compound there is a mixture of different elements. Like in Carbon Dioxide, the symbol is CO2. This shows the carbon (C) and oxygen (O) together. I hope i worded that well enough and this helps :)