Given:

Planet.java

public class Planet {
    public void orbit() {/* Implementation not shown */}
}

Plane.java

public class Plane {
    public void fly() {/* Implementation not shown */}
}

Plant.java

public class Plant {
    public void grow() {/* Implementation not shown */}
}

Main.java

import java.util.ArrayList;

public class Main
{
    public static void main(String[] args)
    {
        ArrayList<Object> objects = new ArrayList<Object>();

        objects.add(new Planet());
        objects.add(new Plane());
        objects.add(new Plant());

        for (Object o : objects) {
            System.out.println(o);
        }
    }
}

What will this program do?

1. Correct Answer
   Incorrect Answer
   a

   Infinite loop

2. Correct Answer
   Incorrect Answer
   b

   Compile Error

3. Correct Answer
   Incorrect Answer
   c

   Runtime error

4. Correct Answer
   Incorrect Answer
   d

   Print object references to the console

5. Correct Answer
   Incorrect Answer
   e

   Print nothing to the console