In Java, which collection class does not allow duplicate elements and is typically implemented as a binary tree?

A. public class Circle implements Shape { private int radius; }B. public abstract class Circle extends Shape { private int radius; }C. public class Circle extends Shape { private int radius; public void draw(); }D. public abstract class Circle implements Shape { private int radius; public void draw(); }E. public class Circle extends Shape { private int radius; public void draw() { /* code here */ } }F. public abstract class Circle implements Shape { private int radius; public void draw() { /* code here */ } }

interface Base{ boolean m1 (); byte m2(short s);}

1. interface Base2 implements Base {}2. abstract class Class2 extends Base { public boolean m1(){ return true; }}3. abstract class Class2 implements Base {}4. abstract class Class2 implements Base { public boolean m1(){ return (7 > 4); }}5. abstract class Class2 implements Base { protected boolean m1(){ return (5 > 7) }}

import java.awt.*;import java.applet.*;public class myapplet extends Applet{ public void paint(Graphics g) { g.drawString("A Simple Applet", 20, 20); }}