Notice that in the design above, the GetDetailsString method has a default implementation and is only overridden by the ChecklistGoal class. Why is the GetDetailsString method only overridden by the class and not the other two derived classes? a. Because overriding it in the one place will provide the functionality to all three. b. Because the default functionality is sufficient for the other classes, but not for the ChecklistGoal class. c. Because the other two have reached their override limit. d. Because it can only be overridden once.