I think that the kids were scared of the step mother so they made heer into a witch in the story
Adjective clauses provide information about some noun in the sentence, which is the same function as adjectives.
So an adjective would be "to tell the interesting story", where interesting gives some information about the story.
Similarly, "which is about wild ponies" is the whole adjective phrase - and this is the correct answer- gives some information about the story.
Answer:
broke sorry thats all I can get from it.