Detailed Instructions: You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.
Q: Category: CHRISTMAS TRADITIONS 
Clue: It's believed this saint began the custom of the nativity scene in 1223, using real people & animals
A:
saint francis of assisi