Aesop's Fables-- is there a singular form?


“The Tortoise and the Hare” is ______.
Which of the following choices do you think is grammatically correct to fill in the blank?

1 an Aesop’s Fable
2 an Aesop Fable
3 an Aesop’s fable
4 an Aesop fable

Thanks in advance.

Referenced in separate post