Creating References Using Inheritance Hierarchies

AP Computer Science A· difficulty 3/5

public class Animal {
    public String sound() { return "?"; }
}
public class Dog extends Animal {
    public String sound() { return "woof"; }
}
public class Cat extends Animal {
    public String sound() { return "meow"; }
}
// Usage:
Animal[] arr = {new Dog(), new Cat(), new Animal()};
for (int i = 0; i < arr.length; i++) {
    System.out.print(arr[i].sound() + " ");
}

What is printed?

A
$? ? ?$
B
$Compile error$
C
$woof woof woof$
D
$woof meow ?$
check_circle

Explanation

Each call uses dynamic dispatch based on actual type: Dog says "woof", Cat says "meow", and the plain Animal returns "?".

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