instruction:
In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
question:
Why could there be reasonable doubt about the validity of what was stated that she said?, Context: In May 2007, The Daily Telegraph, citing unnamed sources, reported that the Queen was "exasperated and frustrated" by the policies of the British Prime Minister, Tony Blair, that she was concerned the British Armed Forces were overstretched in Iraq and Afghanistan, and that she had raised concerns over rural and countryside issues with Blair. She was, however, said to admire Blair's efforts to achieve peace in Northern Ireland. On 20 March 2008, at the Church of Ireland St Patrick's Cathedral, Armagh, the Queen attended the first Maundy service held outside England and Wales. At the invitation of the Irish President, Mary McAleese, the Queen made the first state visit to the Republic of Ireland by a British monarch in May 2011.
answer:
unnamed sources


question:
who avenged Chu'Tsai's forefathers?, Context: Genghis Khan realised that he needed people who could govern cities and states conquered by him. He also realised that such administrators could not be found among his Mongol people because they were nomads and thus had no experience governing cities. For this purpose Genghis Khan invited a Khitan prince, Chu'Tsai, who worked for the Jin and had been captured by the Mongol army after the Jin dynasty was defeated. Jin had captured power by displacing Khitan. Genghis told Chu'Tsai, who was a lineal descendant of Khitan rulers, that he had avenged Chu'Tsai's forefathers. Chu'Tsai responded that his father served the Jin dynasty honestly and so did he; also he did not consider his own father his enemy, so the question of revenge did not apply. This reply impressed Genghis Khan. Chu'Tsai administered parts of the Mongol Empire and became a confidant of the successive Mongol Khans.
answer:
Genghis Khan


question:
How is the system distinctive?, 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.
answer:

Mexico City is the only city in the world to use the icon reference and has become a popular culture trademark for the city