Definition: 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.
Input: Question: Which of the chemical agents used in the Halabja chemical attack was first invented? Passage 1:From 1931, Hermes studied mathematics, physics, chemistry, biology and philosophy at the University of Freiburg. In 1937 he passed the state examination in Münster and was attending there in 1938 when the physicist Adolf Kratzer was present. After that he went on a scholarship to the University of Göttingen and then became an assistant at the University of Bonn. During World War II he was a soldier on the Channel Island of Jersey until 1943 and then on to the Chemical Physics Institute of the Navy in Kiel. At the end of the war he moved to Toplitzsee, where he was tasked with working on new encryption methods. In 1947, he became a lecturer at the University of Bonn where he took his habilitation, his thesis called Analytical manifolds in Riemannian areas. In 1949 he became a Professor at the University of Münster, where he turned back to the subject of mathematical logic.
 Passage 2:Between 1980 and 1988, the conflict intensified as the Iran–Iraq War commenced. One of the groups targeted in particular by Iraqi authorities were the Feyli Kurds, a community of Shi'ite Kurds settled in the southern area of the Zagros Mountains near Iraq's border with Iran. Saddam Hussein considered the group as 'Iranians' and began a campaign to drive the settlers out of the area as a part of his 'Arabization' policy in 1980., Saddam Hussein was severely critical of the Kurdistan Democratic Party (KDP) as they aligned forces with Iran in the conflict. In 1983, to avenge this liaison, he ordered the Army to abduct as many as 8,000 men and boys from Erbil province, where the clan of Barzani Kurds was based. Massoud Barzani, the leader of the clan and the KDP, himself lost 37 members of his family to the Iraqi troops. They were reported to having been sent to Nugra Salman prison in the southern deserts of Iraq, where they were tortured. Subsequently, the remains of 512 Barzani men were discovered in a mass grave. On March 16, 1988, Iraqi troops began shelling the Kurdish town of Halabja, in retaliation for an attack on Iraqi positions carried out by Iranian Revolutionary Guards and the aligned Peshmerga fighters. Subsequently, the town was attacked with a mix of chemical substances such as VX (nerve agent), sarin and mustard gas (see Halabja chemical attack). Over 5,000 people are believed to have been killed in the attack, which was considered to be a part of the Al-Anfal Campaign, directed against Kurds by the government under the command of Ali Hassan al-Majid, head of the Northern Bureau of the Ba'ath Party.
 Passage 3:Construction of the nuclear submarine Ekaterinburg (K-84) began at the Northern Machinebuilding Enterprise (Sevmash) in Severodvinsk on 17 February 1982, before being commissioned into the Soviet Navy on 30 December 1985. She was the second of the seven-boat Project 667BDRM Delfin class, which was developed at the Rubin Design Bureau in September 1975. A ballistic missile submarine, she was designed primarily to carry up to 16 R-29RM Shtil (NATO designation: SS-N-23 Skiff) SLBM for use against military and industrial facilities in the case of a nuclear war. Each Shtil missile carries ten 100 kt multiple independently targeted reentry vehicles, and has a circular error probable of . She is also equipped with RPK-7 Veter (NATO designation: SS-N-16 Stallion) anti-ship missiles for use against large surface vessels, and self-defense torpedoes.

Output:
2