Subclass Default Constructor Implementation

Consider the following class definitions.

public class Animal {
    private int age;
    public Animal() {
        age = 0;
    }
    public Animal(int a) {
        age = a;
    }
    // Other methods not shown
}

public class Dog extends Animal {
    private String breed;
    public Dog() {
        /* implementation not shown */
    }
    // Other methods not shown
}

Which of the following code segments, if substituted for /* implementation not shown */, correctly implements the default constructor for the Dog class?

I. super(1.0); breed = "Unknown";
II. breed = "Unknown"; super();
III. super(); breed = "Unknown";