As stated above, breathing is the biological process of inhaling and exhaling of the gases between the cells and the environment. The mechanism of breathing involves various respiratory structures such as the windpipe, lungs and nose. Respiration, on the other hand, is a chemical process that takes place in the cell.
 
        
                    
             
        
        
        
<span>d. sporangia.
is a structure that can be found in unicellular and multicellular organisms that encloses spores. Organisms that form sporangia in their life cycles are plants, fungi and algae among others.</span>
        
             
        
        
        
<span>The organic molecules that must be included in the soil for earthworm nutrition are Neutral pH. A neutral pH substance that is neither basic nor acidic is considered neutral. The pH scale is the one that measures how a substance is basic or acidic. It ranges from 0-14. A 7 pH is neutral.</span>
 
        
                    
             
        
        
        
C . the square of the distance the separated them
        
                    
             
        
        
        
Answer: E.  reforestation
Explanation:
Reforestation is a process of planting trees in an area so as to conserve the land as future forest. According to the given situation, reforestation is the practice which can be used by the biologists to grow nitrogen fixing plants in an area so as to increase the nutrient concentration of the soil which have been depleted.