问题：

[单选]

1. class Pizza { 
2. java.util.ArrayList toppings； 
3. public final void addTopping（String topping） { 
4. toppings.add（topping）；
5. } 
6. } 
7. public class PepperoniPizza extends Pizza { 
8. public void addTopping（String topping） { 
9. System.out.println（”Cannot add Toppings”）； 
10. } 
11. public static void main（String[] args） { 
12. Pizza pizza = new PepperoniPizza（）； 
13. pizza.addTopping（”Mushrooms”）； 
14. } 
15. } 
What is the result？（） 

A .  Compilation fails.
B .  Cannot add Toppings
C .  The code runs with no output.
D .  A NullPointerException is thrown in Line 4.