It would most likely be B or C since they are the same. Dashes basically show emphasis and if the sentence inside them is taken away, the other parts of the sentence are not affected. If we took the lion part out of your sentence, the sentence would still be talking about symbolism. However it more common to use parenthesis or commas to add emphasis but that's just stylistic choice
I would say C. a poem that tells a story
The Fortunato carnival costume symbolizes a fool or a jester.
