Given the question: Generate a question that has the following answer: Billy's muteness was caused by a raging barnfire. for the following movie plot: A poor farmer struggles to raise his orphaned grandson, who was left mute after a raging barnfire. When a beautiful little calf is born on the farm on Christmas eve, Santa decides she'll make the perfect gift for the boy so he wraps a ribbon around her neck. Santa also leaves the animals with a special gift - they can talk for one day each Christmas, but they must keep it a secret. When the boy discovers the little calf the next day, she unknowingly tries to strike up a conversation with him. The other farm animals decide that, since he can't tell anyone, their secret is still safe. And, Annabelle's mother, Star, tells the little calf that if she is really good, she can ask Santa for something special next Christmas. So the little calf puts on her best attitude every day, and becomes fast friends with the boy over the course of the year. All the while, she is always dreaming of that special wish Santa will grant her, the gift of flying like his reindeer.All seems well on the farm, until the boy's horrid Aunt decides that she'd like a child for Christmas. She hires a crooked lawyer to contrive some way to steal the boy away from his grandfather. The plan he finally comes up with gives her custody of the child until such time as he can speak. It looks like everything is all over for the family when she shows up to claim him on Christmas Eve, but the farm animals devise a plan to keep the hag there overnight by dumping her car in the pond. Later that night, when Santa shows up, Annabelle asks him for her special wish - but it's not the one everyone was expecting. She chooses, instead, to selflessly give her Christmas voice to her mute friend, knowing that she will never speak again as long as she lives. The Aunt's plans are thus foiled - but not to worry because she meets a neighboring farmer with two punky kids that would surely benefit from the type of tough love she's offering.Years into the future, the boy has grown up and married a childhood friend, and old Annabelle is still living in the barn, always...
The answer is:
What caused Billy's muteness?