Teacher: In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
Teacher: Now, understand the problem? If you are still confused, see the following example:
what is the first event mentioned?, Context: The Russian Revolution is the series of revolutions in Russia in 1917, which destroyed the Tsarist autocracy and led to the creation of the Soviet Union. Following the abdication of Nicholas II of Russia, the Russian Provisional Government was established. In October 1917, a red faction revolution occurred in which the Red Guard, armed groups of workers and deserting soldiers directed by the Bolshevik Party, seized control of Saint Petersburg (then known as Petrograd) and began an immediate armed takeover of cities and villages throughout the former Russian Empire.
Solution: Russian Revolution
Reason: This is a good example, and the Russian Revolution is the first event mentioned.

Now, solve this instance: What is the system?, Context: Mexico City is served by the Sistema de Transporte Colectivo, a 225.9 km (140 mi) metro system, which is the largest in Latin America. The first portions were opened in 1969 and it has expanded to 12 lines with 195 stations. The metro is one of the busiest in the world transporting approximately 4.5 million people every day, surpassed only by subway lines in Moscow (7.5 million), Tokyo (5.9 million), and New York City (5.1 million). It is heavily subsidized, and has some of the lowest fares in the world, each trip costing 5.00 pesos from 05:00 am to midnight. Several stations display pre-Columbian artifacts and architecture that were discovered during the metro's construction.[citation needed] However, the metro covers less than half of the total urban area. The Metro stations are also differentiated by the use of icons and glyphs which were proposed for people who could not read. The specific icons were developed based on historical (characters, sites, pre-Hispanic motifs), linguistic, symbolic (glyphs) or location references and has being emulated in further transportations alternatives in the City and in other Mexican cities. Mexico City is the only city in the world to use the icon reference and has become a popular culture trademark for the city.
Student:
Sistema de Transporte Colectivo