Given the uncompleted code of a class：    
class Person { 
String name， department；    
int age； 
public Person（String n）{ 
name = n；
} 
public Person（String n， int a）{ 
name = n； 
age = a； 
} 
public Person（String n， String d， int a） { 
// doing the same as two arguments version of constructor    
// including assignment name=n，age=a    department = d；    
}    
} 
Which expression can be added at the "doing the same as..." part of the constructor？（）