下列程序将类C15的对象写入文件file15．txt，选择正确的语句填入下列程序的横线处。
package ch2;
import jav

A．util.*;
import java.io.*;
class C15______

public iht a;
public void setInt(int newa)

a = newa;


public class Testl5

pulibc static void main(String[] args)

C15 obj = new C15();
try

FileOutputStream fos =newFileOutputStream("ch2\\filel5.txt");
ObjectOutputStream oos = ObjectOutputStream(fos);
Obj.setInt(10);
oos.writeObject(obj);
oos.close ();
fos.close();

catch(IOException ioe)

ioe.printStackTrace();


A. implements RunnableB. implements SedalizableC. extends SerializableD. implements InputStream