(单选题)6: import java.awt.*; public class X extends Frame{ public static void main(String[] args){ X x=new X();x.pack();x.setVisible(true); } public X(){ setLayout(new GridLayout(2,2)); Panel p1=new Panel(); add(p1); Button b1=new Button("One"); p1.add(b1); Panel p2=new Panel();add(p2); Button b2=new Button("Two"); p2.add(b2); Button b3=new Button("Three"); p2.add(b3); Button b4=new Button("Four"); add(b4); } }when the frame is resized,

A: all change height and width

B: Button One change height

C: Button Two change height and Button Three change width

D: Button Four change height and width