Q:Generate a question that has the following answer: He died in the World Trade Center attack. for the following movie plot: Nine-year-old Oskar Schell (Thomas Horn), who suffers from Asperger syndrome, is the son of German American Thomas Schell (Tom Hanks).[5] Thomas would often send Oskar on missions to do something involving one of his riddles. The last riddle he ever gives Oskar is proof that New York City once possessed a Sixth Borough. In a flashback, Thomas and Oskar play a scavenger hunt to find objects throughout New York City. The game requires communication with other people and is not easy for the socially awkward Oskar who is told "If things were easy to find, they wouldn't be worth finding". On September 11, 2001, Oskar and his classmates are sent home from school early while his mother Linda (Sandra Bullock) is at work. When Oskar gets home, he finds five messages from his father on the answering machine saying he is in the World Trade Center. When Thomas calls for the sixth time, although Oskar is present to answer this call, he is too scared to answer. The machine records a sixth message which stops when the building collapses. Oskar knows his father has been killed and falls to the floor. He replaces the answering machine with a new one and hides the old one so his mother will never find out. A few weeks after what Oskar calls "the worst day," he confides in his German grandmother and they become closer. Oskar's relationship with his mother worsens since she cannot explain why the World Trade Center was attacked and why his father died. Oskar tells his mother he wishes it had been her in the building, not his father, and she responds, "So do I". After, Oskar says he did not mean it, but his mother doesn't believe him. A year later, Oskar finds a vase in his father's closet with a key in an envelope with the word "Black" on it. He vows to find what the key fits. He finds 472 Blacks in the New York phone book and plans to meet each of them to see if they knew his father. He first meets Abby Black (Viola Davis), who has recently divorced her husband. She tells Oskar she did not know his father. One day, Oskar...
A:
How did Oskar's father die?