Why does Twain have the cat return at the end of the fable
to reveal the moral of the story?

to reveal how life is unfair and that despite theanimals' genuine curiosity, they could not learn the truth

to highlight the idea that life's most basic truthsare, like the cat, elusive and hard to decipher

to reveal why none of the animals like the cat, as he is always keeping secrets or telling lies

to add ironic humor, as the character whom the
others don't trust actually reveals the truth

The correct choice is D)

Explanation:

All the animals said the Cat was a liar. In a twist of irony, the writer brings back the Cat to make a "closing remark".

The Cat makes the point that people many times see only a reflection of themselves in the text that they read.  

Coming from the Cat whom no one trusted, it was a humorous ending of The Fable.

Cheers!

You forgot to mention that this question is about "A fabula" by Mark Twain.

to add ironic humor, as the character whom the others don't trust actually reveals the truth

Explanation:

The fable talks about an aritsta who painted a picture and I leave it in front of a mirror, so that the image is softened and the picture is more beautiful. The cat, observing what the artist did, was amazed by the beauty and told the other animals how beautiful and elegant the artist's work was. However, some animals did not believe the cat's words and went to look at the artist's work for themselves. However, they positioned themselves between the artist's work and the mirror and were only able to see their own images reflected in the mirror, for this reason, they did not believe in the cat.

For this reason, Twain decides to bring the cat at the end of the story to reveal the moral of the narrative. With that Twain adds an ironic humor, because the character that others do not trust reveals the truth.

answer; ///i believe the answer your looking for and the correct answer is (d); / he becomes very angry;