Question: "A Test Before Trying" is the tenth episode of the 24th season of "The Simpsons", theepisode is dedicated to the memory of Huell Howser, who appeared in the episode "O Brother, Where Bart Thou?", which is he eighth episode of which season?

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A Test Before Trying: "A Test Before Trying" is the tenth episode of the 24th season of "The Simpsons" and the 518th episode overall.  It first aired on the Fox network in the United States on January 13, 2013.  The episode is dedicated to the memory of Huell Howser, who appeared in the episode "O Brother, Where Bart Thou? ".  In the Season 16 episode, "There's Something About Marrying", the travel journalist (who has a similar name), that gave Springfield a score of 6/10, thereby causing the town to lose its tourists was based on him.  The character in that episode was voiced by Karl Wiedergott.

The Haw-Hawed Couple: "The Haw-Hawed Couple" is the eighth episode of "The Simpsons"<nowiki>'</nowiki> eighteenth season.  It first aired on the Fox network in the United States on December 10, 2006.  In the episode, Bart becomes Nelson's new best friend and under Nelson's protection no one dares to mess with Bart.  It was written by Matt Selman and directed by Chris Clements.  In its original run, the episode received 8.29 million viewers.  The episode's title is a pun on "The Odd Couple", emphasizing Nelson's style of laughing.  A fictional character featured in this episode, Angelica Button, was later used in the season 19 episode, "Smoke on the Daughter".

California's Gold: California's Gold is a public television human interest program that explores the natural, cultural, and historical features of California.  The series ran for 24 seasons beginning in 1991, and was produced and hosted by Huell Howser in collaboration with KCET, Los Angeles.  The series ceased production when Howser retired in November 2012, shortly before his death on January 7, 2013, although episodes continued to be shown for some time after his death.  In May 2016, KCET showed a "lost" episode on the Charles F. Lummis House, now considered to be the final episode.

Bart the Daredevil: "Bart the Daredevil" is the eighth episode of "The Simpsons"' second season.  It originally aired on the Fox network in the United States on December 6, 1990.  It was written by Jay Kogen and Wallace Wolodarsky and directed by Wes Archer.  In the episode, the Simpsons go to a monster truck rally that features famous daredevil Lance Murdock.  Bart immediately becomes enamored and decides that he wants to become a daredevil as well.  Bart's first stunt ends in injury, and despite the family and Dr. Hibbert's best efforts, he continues to attempt stunts.

Bart Gets Hit by a Car: "Bart Gets Hit by a Car" is the tenth episode of "The Simpsons"<nowiki>'</nowiki> second season.  It originally aired on the Fox network in the United States on January 10, 1991.  At the start of the episode, Bart is hit by Mr. Burns<nowiki>'</nowiki> car.  Prompted by ambulance-chasing lawyer Lionel Hutz and quack doctor Dr. Nick Riviera, the Simpsons sue Mr. Burns, seeking extensive damages for Bart's injuries.  Hutz and Dr. Nick exaggerate Bart's injuries so they can gain sympathy at the trial.  Marge is against the whole thing and grows concerned with the fact that Homer is asking Bart to lie.

Once Upon a Time in Springfield: "Once Upon a Time in Springfield" is the tenth episode of "The Simpsons"' twenty-first season.  It originally aired on the Fox network in the United States on January 10, 2010.  It was promoted as the 450th episode of the series, but is actually the 451st, and aired alongside "The Simpsons 20th Anniversary Special – In 3-D!  On Ice! ".  The episode is dedicated to Eartha Kitt, who died December 25, 2008, over one year before the episode first aired.

O Brother, Where Bart Thou?: "O Brother, Where Bart Thou?"  is the eighth episode of "The Simpsons"' 21st season.  It originally aired on the Fox network in the United States on December 13, 2009.  In this episode, Bart goes on a quest to get a baby brother out of jealousy of the sisterly bond Lisa has with Maggie.

The Simpsons 138th Episode Spectacular: "The Simpsons 138th Episode Spectacular" is the tenth episode of "The Simpsons"<nowiki>'</nowiki> seventh season.  It originally aired on the Fox network in the United States on December 3, 1995.  As the title suggests, it is the 138th episode and the third clip show episode of "The Simpsons", after "" and "Another Simpsons Clip Show".  While the "138th Episode Spectacular" compiles sequences from episodes throughout the entire series like the previous two, it also shows clips from the original Simpsons shorts from "The Tracey Ullman Show" and other previously unaired material.  Like the Halloween specials, the episode is considered non-canon and falls outside of the show's regular continuity.

The Telltale Head: "The Telltale Head" is the eighth episode of "The Simpsons"<nowiki>'</nowiki> first season.  It originally aired on the Fox network in the United States on February 25, 1990.  It was written by Al Jean, Mike Reiss, Sam Simon and Matt Groening, and directed by Rich Moore.  In the episode, Bart cuts the head off the statue of Jebediah Springfield in the center of town to impress Jimbo, Kearney and Dolph, three older kids he admires.  The town's residents, including the three boys, are horrified and Bart regrets his actions.  After telling his family, Homer and Bart head to the center of town, where they are met by an angry mob.  After Bart tells the mob he has made a mistake, the townspeople forgive Bart and he places the head back on the statue.  The episode's title is a reference to the short story "The Tell-Tale Heart" by Edgar Allan Poe.

To Cur with Love: "To Cur with Love" is the eighth episode of the 24th season of "The Simpsons".  It originally aired on the Fox network in the United States on December 16, 2012.  An alternate cut of this episode was re-aired on December 23, 2012.  It had a few minor changes, including insertion of the Plymptoons couch gag from "Beware My Cheating Bart" that was not included in the original airing.  Also, the final "Montgomery Burns Explains the "Fiscal Cliff"" scene was cut from the original version shown so that the episode still has the same runtime.

Supporting paragraphs: A Test Before Trying O Brother, Where Bart Thou?
Answer: 21st