A sample is termed REPRESENTATIVE SAMPLE  if it has similar characteristics to the population being studied.
The representativeness of a sample is the extent to which its characteristics accurately reflects the characteristics of the population being studied.
        
                    
             
        
        
        
<u><em>hello,</em></u>
<u><em>Vitamin A deficiency</em></u> can cause both temporary and permanent eye damage, and may even lead to blindness. In fact, vitamin A deficiency is the world's leading cause of blindness.<em>Vitamin is most damaging to women,preganant women and increase mortality function.</em>
<em>thanxxxx</em>
<em>heyyya</em>
<em>mark as brainlisttt</em>
 
        
             
        
        
        
Answer:the decline of lichens is an important indicator of an imbalance in the ecosystem. this research can help system ecologists predict how pollution will affect the entire ecosystem 
Explanation:
 
        
                    
             
        
        
        
I’m pretty sure it is Sediments I think