What is the output of this C# code?

What is the output of this C# code?

class Animal {
  public virtual string Speak() => "Animal sound";
}
class Dog : Animal {
  public override string Speak() => "Bark";
}
class Cat : Animal {
  public override string Speak() => "Meow";
}

Animal a = new Dog();
Console.WriteLine(a.Speak());