Question: What British public-service television broadcaster does Celia Valerie Sawyer have the program "Four Rooms"?

Context paragraphs:
Channel 4 Sheffield Pitch: The Channel 4 Sheffield Pitch is an annual competition sponsored by British public-service television broadcaster Channel 4, which seeks to offer one new documentary maker the chance to make a film for the company.  It takes place within the Sheffield International Documentary Festival, and at £30,000 represents the largest single award for documentary film in the UK.

Extreme Celebrity Detox: Extreme Celebrity Detox was a reality television programme on Channel 4, the British public-service television broadcaster, in 2005.

ZDF: Zweites Deutsches Fernsehen (] ; English: Second German Television ), usually shortened to ZDF, is a German public-service television broadcaster based in Mainz, Rhineland-Palatinate.  It is run as an independent nonprofit institution, which was founded by all federal states of Germany ("Bundesländer").  ZDF is financed by television licence fees and advertising revenues.

Karl-Günther von Hase: Karl-Günther von Hase (born 15 December 1917) is a German diplomat and Secretary of State.  He also served as Director General (Intendant) of the ZDF, the German public-service television broadcaster.  Hase served as spokesman of the Press and Information Office of the Federal Government and as ambassador in London.

RASD TV: RASD TV is the Sahrawi state-owned satellite and terrestrial public-service television broadcaster.  Its offices are located in the Sahrawi refugee camps of Tindouf Province, Algeria.

Joseph Hayat: Joseph Hayat is a British journalist and television producer.  Hayat has produced and presented current affairs documentaries such as the likes of "Hayat in Trump's America", "Hayat in The Jungle" and "Hayat in Iraq" for BMTV.  He formerly presented for RT working from their London, UK bureau as well as for the British public-service television broadcaster Channel 4.

V (poem): "V" (sometimes styled "v.") is a poem by Tony Harrison written in 1985.  The poem aroused much controversy when broadcast in film version on British public-service television's Channel 4 due to its extensive use of profanity and racial epithets.  The poem uses profanity directly as well as when quoting graffiti.

Celia Sawyer: Celia Valerie Sawyer (born August 1966) is a businesswoman, interior designer and a dealer both through her own companies and on the Channel 4 programme "Four Rooms".

Televisión Española: Televisión Española (acronym TVE, on lowercase letters: tve, in English "Spanish Television") is the national state-owned public-service television broadcaster in Spain.  TVE belongs to the RTVE Corporation which has overall responsibility for national public-service radio and television under a Parliament-appointed General Manager who, as well as being answerable to a Board of Directors, reports to an all-party committee of the national parliament, as provided for in the Public Radio and Television Law of 2006.

Channel 4: Channel 4 is a British public-service television broadcaster that began transmission on 2 November 1982.  Although largely commercially self-funded, it is ultimately publicly owned; originally a subsidiary of the Independent Broadcasting Authority (IBA), the station is now owned and operated by Channel Four Television Corporation, a public corporation of the Department for Culture, Media & Sport, which was established in 1990 and came into operation in 1993.  With the conversion of the Wenvoe transmitter group in Wales to digital on 31 March 2010, Channel 4 became a UK-wide TV channel for the first time.

Supporting paragraphs: Celia Sawyer Channel 4
Answer: Channel 4