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.

Question: What was the population of Sofia the year that Binding was there to lecture intellectuals? Passage 1:Latin pop became the most popular form of Latin music in the United States during the 1980s and 1990s, with acts such as Puerto Rican boyband Menudo, even achieving massive crossover success among non-Latino listeners during the late 1990s. While not restricted to America by any means, Latin pop was profoundly affected by production techniques and other styles of music — both Latin and otherwise — that originated primarily in the United States. Tejano music, centered in Texas and the U.S./Mexico border region, had begun to introduce synthesizers, slicker production, and a more urban sensibility to formerly root styles like norteño and conjunto. Moreover, New York and Miami were home to thriving Latin club scenes, which during the 1980s led to the rise of Latin freestyle, a club-oriented dance music that was rooted in Latin rhythms but relied on synthesizers and drum machines for most of its arrangements. Both of these sounds influenced the rise of Latin pop, which retained Latin rhythms in its uptempo numbers but relied more on mainstream pop for its melodic sense.
 Passage 2:In planning for the actual attack, Manteuffel had divided his 5th Panzer Army into three corps composed of infantry, tanks, and supporting artillery. The main effort, or schwerpunkt, would consist of XLVII Panzer Corps and LVIII Panzer Corps advancing west across the River Our at Ouren from the south or left flank of the German army front. They would then occupy the transportation center of Bastogne, before crossing the Meuse River at Namur. The third group, LXVI Corps, would advance west on either side of the Schnee Eifel. This northernmost, or right wing, element would flank and begin an envelopment of the American forces occupying fortifications on the Schnee Eifel and then converge on the town of Winterspelt. From there, LXVI Corps would cross the Our river and occupy St. Vith on the first day of the attack. LXVI Corps was the weakest of the three corps, with no attached tank division or motor transport, but did include an attached assault gun battalion. The Panzer Lehr Division (Armor Demonstration Division) and the Führer Begleit Brigade (Führer Escort Brigade) were to be held in reserve, with the Führer Begleit only usable with Model's express permission. Manteuffel's preference for the "little slam", or limited solution, was reflected in the absence of planning beyond reaching the Meuse River.
 Passage 3:In 1860 Binding moved to Göttingen where he studied history and jurisprudence. After a short stay in Heidelberg, where he won a law prize, he moved back to Göttingen to finish his studies. In 1864 he completed his habilitation paper in Latin about Roman criminal law and lectured in criminal law at Heidelberg University. Two years later he was appointed professor of law of state and criminal law and procedure in Basel, Switzerland. In the same year he married Marie Luise Wirsing and published Das burgundisch-romanische Königreich and Entwurf eines Strafgesetzbuches für den Norddeutschen Bund. At this time he also became friends with Johann Jacob Bernoulli - an archaeologist, Jakob Burckhardt - an art historian, and Friedrich Nietzsche - a philosopher. In August 1867 his first son, Rudolf Georg, was born, followed two years later by his second son. Rudolf G Binding later became a famous writer. Karl Binding and his wife were to have one more son and two daughters. In 1869 his family moved to Freiburg, and Binding volunteered to fight in the Franco-Prussian War. Although his lack of military training meant he was unable to serve as a soldier, he was accepted as an orderly and posted to the front, serving in a field hospital. In 1872 he took on a post at the Reichs University in Straßburg. In the same year he moved to Leipzig University, where he was to continue to work for the next 40 years. From 1879 until to 1900 Binding worked in the district court of Leipzig. After becoming Leipzig University's rector and receiving his emeritus, he moved to Freiburg, where his wife died only a few days later at 71 years old. In 1918, during the First World War, Binding left Germany to lecture German soldiers in Macedonia and Bulgarian intellectuals in Sofia.
3