1. import java.io.*； 
2. public class Foo implements Serializable { 
3. public int x， y； 
4. public Foo（ int x， int y） { this.x = x； this.y = y； } 
5. 
6. private void writeObject（ ObjectOutputStream s） 
7. throws IOException { 
8. s.writeInt（x）； s.writeInt（y） 
9. } 
10. 
11. private void readObject（ ObjectInputStream s） 
12. throws IOException， ClassNotFoundException { 
13. 
14. // insert code here 
15. 
16. } 
17. } 
Which code， inserted at line 14， will allow this class to correctly serialize and deserialize？（） 

import java.io.*； 
public class Forest implements Serializable { 
private Tree tree = new Tree（）； 
public static void main（String [] args） { 
Forest f= new Forest（）； 
try { 
FileOutputStream fs = new FileOutputStream（”Forest.ser”）； 
ObjectOutputStream os = new ObjectOutputStream（fs）； 
os.writeObject（f）； os.close（）； 
} catch （Exception ex） { ex.printStackTrace（）； } 
} 
} 
class Tree { } 
What is the result？（）