【单选题】给出下列代码: class Rabbit extends Thread{ public Rabbit(){} public void run(){ System.out.println( " 我是兔子,我可是飞毛腿! " ) ;}} 问在主程序处,如下哪段代码可以创建并启动线程?
A: Runnable r ; r = new Rabbit(); r.start();
B: Rabbit r ; r = new Rabbit(); r.run();
C: Thread r ; r = new Rabbit(); r.run();
D: Rabbit r ; r = new Rabbit(); r.start();