Read the short story: Once upon a time, in a small village, lived a young girl named Lily. On her 10th birthday, which was May 12th, she received a magical locket. A year later, on May 12th, she discovered its power to talk to animals. Three years after that, on her 14th birthday, she used its power to save the village from a dragon. When did Lily discover the locket's power?
A) On her 10th birthday.