Answer:
where is the diagram.....
 
        
             
        
        
        
A. light energy, above the arrow
<span>Photosynthesis is a process wherein light energy is converted into chemical energy. </span>
Components of photosynthesis:
Water
Carbon Dioxide
Light energy, mostly from sunlight, is the main requirement for photosynthesis to occur. 
        
             
        
        
        
If the stimulus reaches the threshold an action potential will be generated. If the stimulus doesn't reach it no action potential will be generated. If the stimulus will be stronger the action potential will have the same amplitude. The refractory period makes it harder to generate an action potential so they decrease the frequency of action potential production.