Answer the following question: Information:  - Perverted Justice Foundation, Inc., more commonly known as Perverted-Justice (also known as PeeJ), is an American organization based in California and Oregon, which investigates, identifies, and publicizes the conduct of adults posing as minors in order to solicit online sexual conversations with actual minors.  - Sylvia Rae Rivera (July 2, 1951  February 19, 2002) was an American gay liberation and transgender activist and drag queen. She was a founding member of both the Gay Liberation Front and the Gay Activists Alliance. With her close friend Marsha P. Johnson, Rivera co-founded the Street Transvestite Action Revolutionaries (STAR), a group dedicated to helping homeless young drag queens and trans women of color.  - The Gay Activists Alliance (GAA) was founded in New York City on December 21, 1969, almost six months after the Stonewall riots, by dissident members of the Gay Liberation Front (GLF). Some early members included Jim Owles, Marty Robinson, Kay Lahusen, Arthur Bell, Arthur Evans, Bill Bahlman, Vito Russo, Sylvia Rivera, Marsha P. Johnson, Jim Coles, Brenda Howard, David Thorstad, Michael Giammetta and Morty Manford (son of Jeanne Manford). GAA's first president was Jim Owles.  - David Thorstad ( born June 6 , 1941 ) is an American political activist engaged with pro-pederast and pro-pedophile activism within the North American Man / Boy Love Association ( commonly known as NAMBLA ) , of which he was a founding member . He was also a former president of New York 's Gay Activists Alliance . Thorstad describes himself as a bisexual pederast and atheist ( former Pentecostal ) who has `` never been charged with violating any sex laws '' .  - The North American Man/Boy Love Association (NAMBLA) is a pedophile and pederasty advocacy organization in the United States. It works to abolish age-of-consent laws criminalizing adult sexual involvement with minors and campaigns for the release of men who have been jailed for sexual contacts with minors that did not involve coercion. The group no longer holds regular national meetings, and as of the late 1990sto avoid local police infiltrationthe organization discouraged the formation of local chapters. Around 1995, an undercover detective discovered there were 1,100 people on the organization's rolls. In 1997, NAMBLA was the largest group in IPCE, an international pro-pedophile activist organization. Since then, the organization has dwindled to only a handful of people, with many members joining online pedophile networks such as DanPedo, BoyChat, and Annabelleigh, according to Xavier Von Erck, director of operations at the anti-pedophile organization Perverted-Justice. As of 2005, a newspaper report stated that NAMBLA was based in New York and San Francisco.  - Brenda Howard (December 24, 1946  June 28, 2005) was an American bisexual rights activist, sex-positive feminist, polyamorist and BDSM practitioner. Howard was an important figure in the modern LGBT rights movement.  - Marsha P. Johnson (August 24, 1945  July 6, 1992) was an African American drag queen, sex worker, and gay liberation activist. A veteran of the Stonewall riots, Johnson was born in Elizabeth, New Jersey and was a popular figure in New York City's gay and art scene from the 1960s to the 1990s. Later in life Johnson became an AIDS activist with ACT UP.  - The City of New York, often called New York City or simply New York, is the most populous city in the United States. With an estimated 2015 population of 8,550,405 distributed over a land area of just , New York City is also the most densely populated major city in the United States. Located at the southern tip of the state of New York, the city is the center of the New York metropolitan area, one of the most populous urban agglomerations in the world. A global power city, New York City exerts a significant impact upon commerce, finance, media, art, fashion, research, technology, education, and entertainment, its fast pace defining the term "New York minute". Home to the headquarters of the United Nations, New York is an important center for international diplomacy and has been described as the cultural and financial capital of the world.  - Vito Russo (July 11, 1946  November 7, 1990) was an American LGBT activist, film historian and author who is best remembered as the author of the book "The Celluloid Closet" (1981, revised edition 1987).  - Kay Lahusen (born January 5, 1930), also known as Kay Tobin Lahusen or Kay Tobin, is the first openly gay American woman photojournalist. Lahusen's photographs of lesbians appeared on several of the covers of "The Ladder" from 1964 to 1966 while her partner, Barbara Gittings, was the editor. Lahusen helped with the founding of the original Gay Activists Alliance (GAA) in 1970, she contributed to a New York-based weekly newspaper named "Gay Newsweekly", and co-authored "The Gay Crusaders" with Randy Wicker. She adopted the surname "Tobin" as a pseudonym for a period of time, but apparently never legally changed her name.  - The Gay Liberation Front (GLF) was the name of a number of gay liberation groups, the first of which was formed in New York City in 1969, immediately after the Stonewall riots, in which police clashed with gay demonstrators.  - The Stonewall riots (also referred to as the Stonewall uprising or the Stonewall rebellion) were a series of spontaneous, violent demonstrations by members of the gay (LGBT) community against a police raid that took place in the early morning hours of June 28, 1969, at the Stonewall Inn, located in the Greenwich Village neighborhood of Manhattan, New York City. They are widely considered to constitute the single most important event leading to the gay liberation movement and the modern fight for LGBT rights in the United States.    After reading the paragraphs above, we are interested in knowing the entity with which 'david thorstad' exhibits the relationship of 'occupation'. Find the answer from the choices below.  Choices: - activist  - advocacy  - author  - dissident  - drag queen  - editor  - fashion  - feminist  - historian  - justice  - lgbt  - major  - member  - photojournalist  - police  - political activist  - president  - sex worker  - worker
Answer:
historian