能将程序补充完整的选项是 class Person {private int a；public int change(int m){return m；} } public class Teacher extends Person {public int b；public static void main(String arg[]){ Person p=new Person(); Teacher t=new Teacher();int i；_____ } }

A．i=m

B．i=b

C．i=a

D．i=change(50)

I get the two of them mixed up       ; they are so similar.

A．at one time

B．at no time

C．in no time

D．all the time