Please answer the following question: Question: Who is Fluffy? If there is no answer, please output "Insufficient information to provide an answer.". Movie title: Harry Potter and the Philosopher's Stone Context: Further information: Plot of the novel Harry Potter is a seemingly ordinary boy, living with his neglectful relatives the Dursleys, in Surrey, England. On his eleventh birthday Harry discovers from a mysterious stranger, Rubeus Hagrid, that he is actually a wizard, famous in the Wizarding World for surviving an attack by the evil Lord Voldemort when Harry was only a baby. Voldemort killed Harry's parents, but his attack on Harry rebounded leaving only a lightning-bolt scar on Harry's forehead and rendering Voldemort powerless. Hagrid reveals to Harry that he has been invited to attend Hogwarts School of Witchcraft and Wizardry. After buying his school supplies from the hidden London street, Diagon Alley, Harry boards the train to Hogwarts via the concealed Platform 9 in King's Cross Station. On the train Harry meets Ron Weasley, a boy from a large but poor pure-blood wizarding family, and Hermione Granger, a witch born to non-magical parents. Once they arrive Harry and all the other first-year students are sorted between four houses: Gryffindor, Hufflepuff, Ravenclaw, and Slytherin. Because Slytherin is noted for being the house of darker wizards and witches, Harry convinces the Sorting Hat not to put him in Slytherin. He ends up in Gryffindor along with Ron and Hermione. Ron's older brothers were all placed in Gryffindor as well: mischievous twins Fred and George, Percy the prefect, Charlie (who researches dragons in Romania) and Bill (who works for Gringotts Bank). At Hogwarts Harry begins learning wizardry and discovers more about his past and his parents. He gets recruited for Gryffindor's Quidditch (a sport in the wizarding world where people fly on broomsticks) team as a Seeker, as his father was before him. One night he, Ron, and Hermione discover a large three-headed dog named Fluffy (owned by Hagrid) on a restricted floor in the school. They later find out Fluffy is guarding the Philosopher's Stone, an item that can be used to grant its owner immortality. Harry concludes that his potions teacher,...
A:
a large three-headed dog