Detailed Instructions: In this task, you're given a question, along with three passages, 1, 2, and 3. Your job is to determine which passage can be used to answer the question by searching for further information using terms from the passage. Indicate your choice as 1, 2, or 3.
Problem:Question: What job did Niels Bohr hold the year Barschall emigrated to the United States? Passage 1:In 1998, Kristol and Kagan advocated regime change in Iraq throughout the Iraq disarmament process through articles that were published in the New York Times. Following perceived Iraqi unwillingness to co-operate with UN weapons inspections, core members of the PNAC including Richard Perle, Paul Wolfowitz, R. James Woolsey, Elliot Abrams, Donald Rumsfeld, Robert Zoellick, and John Bolton were among the signatories of an open letter initiated by the PNAC to President Bill Clinton calling for the removal of Saddam Hussein. Portraying Saddam Hussein as a threat to the United States, its Middle East allies, and oil resources in the region, and emphasizing the potential danger of any weapons of mass destruction under Iraq's control, the letter asserted that the United States could "no longer depend on our partners in the Gulf War to continue to uphold the sanctions or to punish Saddam when he blocks or evades UN inspections." Stating that American policy "cannot continue to be crippled by a misguided insistence on unanimity in the UN Security Council," the letter's signatories asserted that "the U.S. has the authority under existing UN resolutions to take the necessary steps, including military steps, to protect our vital interests in the Gulf." Believing that UN sanctions against Iraq would be an ineffective means of disarming Iraq, PNAC members also wrote a letter to Republican members of the U.S. Congress Newt Gingrich and Trent Lott, urging Congress to act, and supported the Iraq Liberation Act of 1998 (H.R.4655) which President Clinton signed into law in October 1998.
 Passage 2:In the early 1940s, he met Pearl Primus at the National Youth Administration and became her first dance partner before studying dance with Syvilla Fort and Katherine Dunham. After serving in World War II, he returned to New York in 1946 first performing on Broadway in Show Boat, and in London in Finian’s Rainbow. Later, Nash became a member of Donald McKayle’s company, another African American choreographer of New York. He became a regular in Broadway originals, performing in My Darlin' Aida, Flahooley, and Bless You All. He also danced with Alvin Ailey in 1954 when he danced in House of Flowers, choreographed by Pearl Bailey. Starting in 1948, Joseph Nash became a dance instructor at Marion Cuyjet’s Judimar School of Dance in Philadelphia. His classes became famous in the city dance scene. One of his most talented students, Judith Jamison, became a world-famous dancer, becoming the artistic director of the Alvin Ailey American Dance Theater. Arthur Hall, a dancer and archivist, was also one of his students.
 Passage 3:Barschall was born as Heinrich Hermann Barschall in Berlin, Germany; his father was a patent attorney who had received a Ph.D. in chemistry after studying with Nobel Laureates Emil Fischer and Fritz Haber. After beginning study in several universities in Germany, he emigrated to the United States in 1937 during the early Holocaust period; though raised as a Lutheran, he had some Jewish ancestry. He received his Ph.D. from Princeton University in 1940 under the direction of Rudolf Ladenburg; he also worked closely with John A. Wheeler. After a suggestion by Niels Bohr, he carried out in only a few days with fellow graduate student Morton H. Kanner the first demonstration of fission by fast neutrons and thorium and uranium. His thesis was on the interaction of fast neutrons with helium. In a paper with John A. Wheeler he reported the discovery of spin-orbit coupling in neutron scattering.

Solution:
3