在程序的下面线处应填入的选项是______。
public class Test______
public static void main(String args[])
Test t=new Test();
Thread tt=new Thread(t);
tt. start();

public void run()
for(int i=0; i＜5; i++)
System. out. println("i="+i);

A．implements Runnable
B．extends Thread
C．implements Thread
D．extends Runnable