选择正确的语句填入下列程序的横线处。 import java.awt.*; import java.awt.event.*; public class ex21 { static Frame f; static FileDialog fd; public static void main(String[] args) {f = new Frame("ex21");______fd. setVisible (true);System.out.println (fd.getFile ()); } }
A.new FileDialog(f, "FileDialog");
B.new FileDialog("FileDialog");
C.fd = new FileDialog(f, "FileDialog");
D.fd = new FileDialog("FileDialog");