Teacher:In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.
Teacher: Now, understand the problem? Solve this instance: Passage: Plants vs. Zombies uses many cultural references in its names of stages and others. The gravestones' inscriptions ("Expired", "Ceased to Exist", "Just Resting", etc.) were taken from Monty Python's "Dead Parrot sketch". Three of the mini-games"Zombiquarium", "Beghouled" and "Beghouled Twist"take their names from two other PopCap games: Insaniquarium, Bejeweled and Bejeweled Twist respectively. Two levels in "vasebreaker" puzzles, "Scary Potter" and "Ace of Vase", take their names from Harry Potter and Ace of Base. Similarly, the "I, Zombie" (a reference to Isaac Asimov's "I, Robot") puzzles have levels called "Dead Zeppelin" (resembling Led Zeppelin) and "All your brainz r belong to us" (a play on the gaming meme "All your base are belong to us"). The name of the Torchwood plant is a reference to Doctor Who and its spin-off show Torchwood. Originally, the dancing zombie resembled Michael Jackson from the short film "Thriller". Though the Jackson-inspired zombie was present in the game before Jackson's death, the estate of Michael Jackson objected to its inclusion more than a year after his death; PopCap agreed to remove the Jackson-inspired zombie and replaced it with a more generic disco-dancing one for all future patches and releases of the game. A "disclaimer" in the game's almanac states "Any resemblance between Dancing Zombie and any persons living or dead is purely coincidental." Some Plants vs. Zombies advertisements parody controversial Evony ads, showing a drooling zombie instead of a voluptuous woman.
Link Information: The "Dead Parrot Sketch", alternatively and originally known as the "Pet Shop Sketch" or "Parrot Sketch", is a sketch from Monty Python's Flying Circus. A satire on poor customer service, it was written by John Cleese and Graham Chapman and initially performed in the show's first series, in the eighth episode ("Full Frontal Nudity", which first aired 7 December 1969). Answer: 1969
Student:
In what year did the sketch that inspired the gravestone inscriptions in Plants vs. zombies first air on television?