It would be D Democritus
He contributed in around 460-370 BC
Whereas the others contributed much later from around 1700's - 1900's
        
             
        
        
        
Visible light is safe for animals because it provides them with warmth.
        
             
        
        
        
10 levels of organization:
Cell
Tissue
Organ
Organ system
Organism
Population
Community
Ecosystem
Biome
Biosphere
If you just look at the next level on the organization levels, you receive a POPULATION.