Question: What position did Cristian Dario Alvarez play for the Spanish football team based in Zaragoza?

full_context: Document 1: Deportivo Aragón: Real Zaragoza Deportivo Aragón is the reserve team of Real Zaragoza, a Spanish football club based in Zaragoza, in the autonomous community of Aragon. Founded as an independent club in 1964, currently plays in Segunda División B – Group 3, holding home matches at "Ciudad Deportiva del Real Zaragoza", with a capacity of 1,000 seats.
Document 2: David de Gea: David de Gea Quintana (] ; born 7 November 1990) is a Spanish professional footballer who plays as a goalkeeper for English club Manchester United and the Spain national team. He has been hailed as one of the best goalkeepers in the world.
Document 3: Daniel Gonzalez (Argentine footballer): Daniel González is a retired Argentine association football goalkeeper who played professionally in Argentina and the United States. He is the goalkeeper coach for Los Angeles Galaxy II, the reserve team for Major League Soccer's Los Angeles Galaxy
Document 4: CB Zaragoza: Club Baloncesto Zaragoza is a basketball team based in Zaragoza, Aragón, who played from 1981 to 1996 in the top Spanish league (Liga ACB since 1983) and nowadays plays in the 1ª División, the fifth tier. Most of the years in which the team played in Liga ACB, CB Zaragoza was also known as CAI Zaragoza for sponsorship reasons.
Document 5: Iker Casillas: Iker Casillas Fernández (] ; born 20 May 1981) is a Spanish professional footballer who plays for Portuguese club Porto and the Spain national team as a goalkeeper. Having won the IFFHS World's Best Goalkeeper Award for a record five consecutive years, Casillas is considered as one of the greatest and most successful goalkeepers of all time, placing second behind Gianluigi Buffon in both the IFFHS Best Goalkeeper of the past decade and quarter-century awards in 2010. Nicknamed ""San Iker"" ("Saint Iker") for his ability to produce spectacular saves, he is an athletic goalkeeper, known for his quick reactions and outstanding shot-stopping ability.
Document 6: Sergio Romero: Sergio Germán Romero (born 22 February 1987) is an Argentine professional footballer who plays as a goalkeeper for English club Manchester United and the Argentina national team.
Document 7: Real Sociedad: Real Sociedad de Fútbol, S.A.D., more commonly referred to as Real Sociedad (] ; "Royal Society") or La Real, is a Spanish football club based in the city of San Sebastián, Basque Country, founded on 7 September 1909. It plays its home matches at the 32,000-capacity Anoeta Stadium. Real Sociedad won the Liga title in 1980–81 and 1981–82, and last finished runners-up in 2002–03. The club has also won the Copa del Rey twice, in 1909 and 1987. It contests the Basque derby against rivals Athletic Bilbao. Real Sociedad were founder members of La Liga in 1928, and its longest spell in the top flight was for 40 seasons, from 1967 to 2007.
Document 8: Zaragoza CD: Real Zaragoza Club Deportivo and later simply Zaragoza Club Deportivo was a Spanish football club based in Zaragoza, founded in 1925 as result of the merger of Athletic Stadium (founded on 1919) and Zaragoza FC (founded on 1921). The club played its games at Campo de la Torre de Bruil, on 1932 merged with Iberia SC to form the current Real Zaragoza.
Document 9: Real Zaragoza: Real Zaragoza, S.A.D. (] ) is a Spanish football team based in Zaragoza, in the autonomous community of Aragon. Founded on 18 March 1932 it currently plays in Segunda División, holding home games at "La Romareda", which seats 34,596 spectators.
Document 10: Cristian Darío Álvarez: Cristian Darío Álvarez (born 13 November 1985) is an Argentine professional footballer who plays for Spanish club Real Zaragoza as a goalkeeper.
Document 11: CD Leganés: Club Deportivo Leganés, S.A.D. is a Spanish football team from Leganés, in the Madrid outskirts. Founded on 26 June 1928 it currently plays in the Primera División, holding home games at "Estadio Municipal de Butarque", which seats 11,454 spectators.
Document 12: Sergio Agüero: Sergio Leonel "Kun" Agüero (] ; born 2 June 1988) is an Argentine professional footballer who plays as a striker for Premier League club Manchester City and the Argentina national team.
Document 13: RSD Santa Isabel: Real Sociedad Deportiva Santa Isabel is a Spanish football team based in Zaragoza, in the autonomous community of Aragón. Founded in 1970, it plays in Regional Preferente de Aragón, holding home games at "César Lainez", with a 1,000-seat capacity.
Document 14: José Guadalupe Martínez: José Guadalupe Martínez Álvarez (born January 27, 1983) is a Mexican goalkeeper for the team Estudiantes Tecos, the Mexican professional football club associated with the Universidad Autónoma de Guadalajara AC. Álvarez made his debut with the club Tecos UAG in 2002.
Document 15: Iberia SC: Iberia Sport Club was a Spanish football club based in Zaragoza, Aragon. The club was founded in 1916, and played its games at Estadio Torrero, on 1932 merged with Zaragoza Club Deportivo to form the current Real Zaragoza.
ground_truth: as a goalkeeper.