Question: The "SS Sonderkommando Sobibor" presided over which numbered Euthanasia Program?

Context paragraphs:
Paul Nitsche: Hermann Paul Nitsche (November 25, 1876 – March 25, 1948) was a German psychiatrist known for his expert endorsement of the Third Reich's euthanasia authorization and who later headed the Medical Office of the T-4 Euthanasia Program.

Dov Freiberg: Dov Freiberg (15 May 1927 – March 2008) born Berek Freiberg, was a Holocaust survivor, writer, and witness at the Eichmann trial and the Demjanjuk case.  During World War II, selected by the SS to join the "Sonderkommando" work unit, Freiberg participated in the Sobibor prisoners' revolt in October 1943, and managed to escape into nearby woods and survived until the Soviet Army liberated the region in July 1944.

Karl Brandt: Karl Brandt (January 8, 1904 – June 2, 1948) was a German physician and "Schutzstaffel" (SS) officer in Nazi Germany.  Trained in surgery, Brandt joined the Nazi Party in 1932 and became Adolf Hitler's escort physician in August 1934.  A member of Hitler's inner circle at the Berghof, he was selected by Philipp Bouhler, the head of Hitler's Chancellery, to administer the "Aktion T4" euthanasia program.  Brandt was later appointed the Reich Commissioner of Sanitation and Health ("Bevollmächtigter für das Sanitäts- und Gesundheitswesen").  Accused of involvement in human experimentation and other war crimes, Brandt was indicted in late 1946 and faced trial before a U.S. military tribunal along with 22 others in "United States of America v. Karl Brandt, et al".  He was convicted, sentenced to death, and later hanged on June 2, 1948.

Siegfried Graetschus: Siegfried Graetschus (9 June 1916 – 14 October 1943) was a German SS functionary at the Sobibor extermination camp during Operation Reinhard, the deadliest phase of the Holocaust in occupied Poland.  He was assassinated by a "Sonderkommando" prisoner during the Sobibor uprising.

Belzec trial: The Belzec trial (German: "Belzec-Prozess" , Polish: "proces Bełżec" ) in the mid-1960s was a war crimes trial of eight former SS members of Bełżec extermination camp.  The trial was held at the 1st Munich District Court ("Landgericht München I") and should be seen in the context of the Sobibor trial, which followed the Belzec trial, because five of the defendants were accused in both trials.  In addition, the Belzec and Sobibor trials, along with the Treblinka trials, form a body of evidence of the crimes of mass extermination as part of the so-called Action Reinhardt programme - the killing of over two million Jews and 50,000 Roma and Sinti.  These trials are directly related to the mass murder of 100,000 people in the official Nazi Euthanasia programme known after the war as Action T4, as many of the security guards worked in the euthanasia centres before transferring to the extermination camps.  The first Euthanasia trials were carried out shortly after the war.

Philipp Bouhler: Philipp Bouhler (11 September 1899 – 19 May 1945) was a senior Nazi Party official who was both a "Reichsleiter" (National Leader) and Chief of the Chancellery of the Führer of the NSDAP.  He was also an SS-"Obergruppenführer" in the "Allgemeine SS" who was responsible for the Nazi "Aktion T4" euthanasia program that killed more than 70,000 handicapped adults and children in Nazi Germany, as well as co-initiator of "Aktion 14f13", also called "Sonderbehandlung" ("special treatment"), that killed 15,000–20,000 concentration camp prisoners.

Franz Stangl: Franz Paul Stangl (26 March 1908 – 28 June 1971) was an Austrian-born police officer, who became an employee of the T-4 Euthanasia Program and an SS commander in Nazi Germany.  He was the commandant of the Sobibór and Treblinka extermination camps during the Operation Reinhard phase of the Holocaust.  He worked for Volkswagen do Brasil and was arrested in Brazil in 1967, extradited to West Germany and tried for the mass murder of 900,000 people.  In 1970 he was found guilty and sentenced to the maximum penalty, life imprisonment.  He died of heart failure six months later.

Sobibór Museum: The Sobibór Museum or the Museum of the Former Sobibór Nazi Death Camp (Polish: "Muzeum Byłego Hitlerowskiego Obozu Zagłady w Sobiborze" ), is a Polish state-owned museum devoted to remembering the atrocities committed at the former Sobibor extermination camp located on the outskirts of Sobibór near Lublin.  The Nazi German death camp was set up in occupied Poland during World War II, as part of the Jewish extermination program known as the Operation Reinhard, which marked the most deadly phase of the Holocaust in Poland.  The camp was run by the "SS Sonderkommando Sobibor" headed by Franz Stangl.  The number of Jews from Poland and elsewhere who were gassed and cremated there between April 1942 and October 14, 1943 is estimated at 250,000; possibly more, including those who came from other Reich-occupied countries.

Memorandum Authorizing Involuntary Euthanasia: Adolf Hitler signed a memorandum authorizing involuntary euthanasia in October 1939 to serve as the legal basis for Aktion T4, the Nazi forced euthanasia program.  Its purpose was to assure the doctors and nurses who took part in the euthanasia program would not be prosecuted for murder.  During the postwar trials of these same individuals, they attempted to use this decree as a justification for their actions.

Max de Crinis: Professor Maximinus Friedrich Alexander de Crinis (29 May 1889 in Ehrenhausen near Graz – 2 May 1945 in Stahnsdorf near Berlin) held a Chair in psychiatry in Cologne and Berlin, and was a medical expert for the Action T4 Euthanasia Program who wrote the Euthanasia Decree, signed by Adolf Hitler on September 20, 1939.

Supporting paragraphs: Sobibór Museum Franz Stangl
Answer: T-4 Euthanasia Program