Consider the following Java program. Which one of the following is an interface?

import java. awt. event\.\*;
import javax. swing\.\*;
public class MouseWhisperer extends JFrame implements MouseListener {
MouseWhisperer() {
super("COME CLOSER");
setSize(300,100);
setDefaultCloseOperation(JFrame. EXIT_ON_CLOSE);
addMouseListener(this);
setVisible(true);
}
public void mouseClicked(MouseEvent e) { setTitle("OUCH"); }
public void mousePressed(MouseEvent e) { setTitle("LET GO"); }
public void mouseReleased(MouseEvent e) { setTitle("WHEW"); }
public void mouseEntered(MouseEvent e) { setTitle("I SEE YOU"); }
public void mouseExited(MouseEvent e) { setTitle("COME CLOSER"); }
public static void main(String[] args) { new MouseWhisperer(); }
}

Select one:

a) addMouseListener(this);
b) public class MouseWhisperer extends JFrame implements MouseListener {
c) public static void main(String[] args) { new MouseWhisperer(); }
d) public void mouseEntered(MouseEvent e) { setTitle("I SEE YOU"); }
e) setVisible(true);