Question: Christian Witkin, is a New York based fashion and portrait photographer, and is well known for his extensive campaigns for which American worldwide clothing and accessories retailer?

Context paragraphs:
Provogue: Provogue is an Indian clothing and accessories retailer based in Mumbai, Maharashtra.  It was launched in 1997 as a menswear fashion brand for contemporary clothing.  Over the years the brand has expanded its collection of men’s and women’s fashion apparel and accessories.

Suzanne Lee: Suzanne Lee (born 1970) is a Brooklyn, New York based fashion designer working on fashion and future technologies.

Hobbs Ltd: Hobbs is a women’s clothing, footwear and accessories retailer based in London, UK.  It was founded in Hampstead in 1981 and began as a shoe retailer.  Hobbs now has stores across the United Kingdom and concession stores in the United States and Germany.  The online store serves 55 countries worldwide.  Hobbs is popularly associated with clothing priced in the mid range for a customer base that is largely middle-aged and older.  Among its best-known customers are the Duchess of Cambridge and her sister, Pippa Middleton.

Rodney Smith (photographer): Rodney Lewis Smith (December 24, 1947 – December 5, 2016) was a New York based fashion and portrait photographer.

Christian Witkin: Christian Witkin (born October 15th, 1966 in Manchester, England) is a New York based fashion and portrait photographer.  He is well known for capturing revealing moments of celebrities - including President Barack Obama, Meredith Vieira, Steve Jobs, Lil' Kim, Quentin Tarantino, Foxy Brown, and Christopher Hitchens - as well as for his extensive campaigns for Gap Inc., Vanity Fair, and People.  His work is described as "iconic, beautiful portraiture defined by a refined yet approachable point of view."

Zara (retailer): Zara (] ) is a Spanish clothing and accessories retailer based in Arteixo, Galicia.  The company was founded in 1975 by Amancio Ortega and Rosalía Mera.  It is the main brand of the Inditex group, the world's largest apparel retailer.  The fashion group also owns brands such as Massimo Dutti, Pull and Bear, Bershka, Stradivarius, Oysho, Zara Home, and Uterqüe.  Zara as of 2017 manages up to 20 clothing collections a year.

Torkil Gudnason: Torkil Gudnason (born in Denmark) is a New York based fashion photographer.

Jason Bell (photographer): Jason Bell (born 19 April 1969 in Camden Town, London) is an English portrait and fashion photographer.  He studied politics, philosophy and economics at Oxford University before returning to London to work for the Sunday Times.  He lives in both New York and London.  He describes photography as 'always part of who I was' and he sees himself as a portrait photographer rather than a fashion photographer, saying: 'for me the most important thing is the person'.

Richard Avedon: Richard Avedon (May 15, 1923 – October 1, 2004) was an American fashion and portrait photographer.  An obituary published in "The New York Times" said that "his fashion and portrait photographs helped define America's image of style, beauty and culture for the last half-century".

Gap Inc.: The Gap, Inc., commonly known as Gap Inc. or Gap, (stylized as GAP) is an American worldwide clothing and accessories retailer.

Supporting paragraphs: Christian Witkin Gap Inc.
Answer: Gap, Inc.