These lines (there is four of them) are residuals of the fusion of the five sacrum vertebrae that are fused. These "vertebrae" or segments present a characteristics, being the first of them very similar to a lumbar vertebra, large, and the other vertebrae are<span> progressively smaller and flattened. They also present a curved shape being anteriorly concave.</span>
        
             
        
        
        
Explanation:
soil organisms which range in size from microscopic cells that digest decaying organic material to small mammals that live primarily on other soil organisms play an important role in maintaining fertility structure drainage and aeration of soil
 
        
             
        
        
        
Answer:
Option D, renewable resource
Explanation:
A renewable resource is the resource  which can be replenished after every use. Or in general the time taken by it to replenish must be small. For instance, fossil fuels too are renewable but the time taken by them to renew is too high and hence they are also considered as non-renewable.  
Also renewable resources can be used again and again.  
Hence, option D is correct