Answer is A 
Firstly axon must reach the threshold level and then depolarisation occurs. Depolarisation phrase means sodium enters and potassium leaves the axon . Choice C can't be because main idea is the entering of sodium ions.
        
             
        
        
        
Answer:
A = rough er
B = chloroplast
D = Cytoplasm 
C = most likely a lysosome
E = cell wall
 
        
             
        
        
        
Plant cells have a cell wall that adds an additional layer of protection from the external environment.
 
        
             
        
        
        
Well the answer you dont have on there is DNA