Question: Who developed the American television series which have "Love and Marriage" as its 20th episode of the third season?

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Time Has Come Today (Grey's Anatomy): "Time Has Come Today" is the first episode of the third season of the American television medical drama "Grey's Anatomy", and the show's 37th episode overall.  Written by Shonda Rhimes and directed by Daniel Minahan, the episode aired on the American Broadcasting Company (ABC) in the United States on September 21, 2006.  The episode primarily focuses on Dr. Izzie Stevens (Katherine Heigl) coping with the unexpected death of her fiancé, Denny Duquette (Jeffrey Dean Morgan), while dealing with the decision to quit the internship program.  Further storylines include Dr. Preston Burke (Isaiah Washington) facing the repercussions of his being shot, and Dr. Meredith Grey (Ellen Pompeo) dealing with the aftermath of her affair with Dr. Derek Shepherd (Patrick Dempsey), which puts a strain in his already troubled marriage to Dr. Addison Montgomery-Shepherd (Kate Walsh).

List of Lupin III Part II episodes (season 3): This is a list of season 3 episodes of the 1977–1980 Japanese animated television series "Lupin the Third Part II" (also known as "Shin Lupin III" or simply as "Lupin III" for the American market) produced by the Japanese animation studio Tokyo Movie Shinsha.  The third season, which contains 52 episodes, aired between October 2, 1978 and October 1, 1979 on the Japanese television network NTV (Nippon Television).  Twenty-six episodes of English adaptation of the anime aired on Adult Swim starting on January 13, 2003, while episode 79 (the 28th episode of the third season) was the last episode to be released dubbed into English.  During the run of the third season, the first Lupin III animated film, "Mystery of Mamo, "debuted in Japanese theaters.  The anime is based on the Lupin III manga written by Monkey Punch beginning in 1967.

Seed (The Walking Dead): "Seed" is the first episode of the third season and 20th episode overall of the post-apocalyptic horror television series "The Walking Dead", which aired on AMC in the United States and in Canada on October 14, 2012.  The episode was written by showrunner Glen Mazzara and directed by Ernest Dickerson.  It is set eight months after the second season finale and focuses on Rick Grimes (Andrew Lincoln) and his group of survivors' discovering and entering the prison complex shown on the previous episode.  Meanwhile, Michonne (Danai Gurira) cares for an ailing Andrea (Laurie Holden).

The Last Walt: "The Last Walt" is the 20th episode of the third season of the American sitcom "Modern Family" and the series' 68th episode overall.  This episode originally aired on ABC on April 18, 2012.  It was written by Dan O'Shannon, Paul Corrigan & Brad Walsh and directed by Michael Spiller.

The Fall Issue: "The Fall Issue" is the 24th episode in the third season, the 65th episode overall and the third season finale of the American dramedy series "Ugly Betty", which aired on May 21, 2009.  This episode doubles as the second part of a two-hour episode, a first in the series' history.

Love and Marriage (M*A*S*H): "Love and Marriage" is the 20th episode of the third season of "M*A*S*H".  It was originally broadcast on February 18, 1975.

M*A*S*H (TV series): M*A*S*H is a 1972–1983 American television series developed by Larry Gelbart, adapted from the 1970 feature film "MASH" (which was itself based on the 1968 novel "", by Richard Hooker).  The series, which was produced with 20th Century Fox Television for CBS, follows a team of doctors and support staff stationed at the "4077th Mobile Army Surgical Hospital" in Uijeongbu, South Korea during the Korean War.  The show's title sequence features an instrumental-only version of "Suicide Is Painless", the theme song from the original film.  The show was created after an attempt to film the original book's sequel, "M*A*S*H Goes to Maine", failed.  The television series is the best-known version of the "M*A*S*H" works, and one of the highest-rated shows in U.S. television history.

Flashes Before Your Eyes: "Flashes Before Your Eyes" is the 8th episode of the third season of the American drama television series "Lost", and the show's 57th episode overall.  The episode was written by the series co-creator, show runner and executive producer Damon Lindelof and supervising producer Drew Goddard, and directed by Jack Bender.  It first aired in the United States on February 14, 2007, on the American Broadcasting Company.  The episode received mostly positive reviews from critics.  Lindelof and Goddard were nominated for the Writers Guild of America (WGA) Award for Best Episodic Drama at the February 2008 ceremony for writing the episode.

Wishin' and Hopin' (Grey's Anatomy): "Wishin' and Hopin'" is the fourteenth episode of the third season of the American television medical drama "Grey's Anatomy", and the show's 50th episode overall.  It was written by Tony Phelan and Joan Rater and directed by Julie Anne Robinson.  The episode originally aired on the American Broadcasting Company (ABC) in the United States on February 1, 2007.  In the episode, Dr. Meredith Grey (Ellen Pompeo) struggles with her Alzheimer's-stricken mother, Ellis Grey (Kate Burton), becoming temporarily lucid.  Further storylines include Dr. Izzie Stevens (Katherine Heigl) and Dr. Miranda Bailey (Chandra Wilson) continuously seeking patients for their new clinic, Dr. Richard Webber (James Pickens, Jr.) dealing with the repercussions of his upcoming retirement, and Dr. George O'Malley (T.R. Knight) facing negative response from colleagues on his unexpected marriage to Dr. Callie Torres (Sara Ramirez).

The Price of Free and Fair Elections: "The Price of Free and Fair Elections" is the 18th episode and season finale of the third season of the American political thriller television series "Scandal", and is the 47th overall episode.  It aired on April 17, 2014 on ABC in the United States.  The episode was written by showrunner Shonda Rhimes and executive producer Mark Wilding and directed by executive producer Tom Verica.  The season finale was originally supposed to be the 22nd episode, but because of the show's lead Kerry Washington's pregnancy, the episode count was trimmed by ABC by four episodes, leading the season finale to be the 18th episode.

Supporting paragraphs: Love and Marriage (M*A*S*H) M*A*S*H (TV series)
Answer: Larry Gelbart