Question: Who is the mother of Tsarevich Ivan Ivanovich, of the country where the operator of 81-740/741 was bombed in August 2004?

full_context: Document 1: 2004 Madrid train bombings: The 2004 Madrid train bombings (also known in Spain as 11-M) were nearly simultaneous, coordinated bombings against the Cercanías commuter train system of Madrid, Spain, on the morning of 11 March 2004 – three days before Spain's general elections. The explosions killed 193 people and injured around 2,000. The bombings constituted the deadliest terrorist attack carried out in the history of Spain and the deadliest in Europe since the 1988 bombing of Pan Am Flight 103 over Lockerbie, Scotland. The official investigation by the Spanish judiciary found that the attacks were directed by an al-Qaeda terrorist cell, although no direct al-Qaeda participation has been established. Although they had no role in the planning or implementation, the Spanish miners who sold the explosives to the terrorists were also arrested.
Document 2: Jaish-e-Mohammed: An informant, posing as a member of Jaish-e-Mohammed, helped police to arrest four people allegedly plotting to bomb a New York City synagogue as well as to shoot Stinger missiles at military aircraft in the United States. The arrest of the four took place in May 2009. One of the four, by the name of James Cromitie, allegedly expressed the desire to join Jaish-e-Mohammed. This expression allegedly took place approximately a year prior to this arrest.
Document 3: Grand Duchess Xenia Alexandrovna of Russia: Grand Duchess Xenia Alexandrovna of Russia (; – 20 April 1960) was the elder daughter and fourth child of Tsar Alexander III of Russia and Empress Maria Feodorovna of Russia (née Princess Dagmar of Denmark) and the sister of Emperor Nicholas II. She married a cousin, Grand Duke Alexander Mikhailovich of Russia, with whom she had seven children. She was the mother-in-law of Felix Yusupov and a cousin of Grand Duke Dmitri Pavlovich of Russia who, together, killed Grigori Rasputin, holy healer to her nephew, the haemophiliac Tsarevich Alexei Nikolaevich of Russia. During her brother's reign she recorded in her diary and letters increasing concern about his rule. After the fall of the monarchy in February 1917, she fled Russia, eventually settling in the United Kingdom. Her grandson Prince Andrew Andreevich has been a head of the Romanov Family since December 2016.
Document 4: List of Russian monarchs: The Time of Troubles came to a close with the election of Michael Romanov as Tsar in 1613. Michael officially reigned as Tsar, though his father, the Patriarch Philaret (died 1633) initially held the real power. However, Michael's descendents would rule Russia, first as Tsars and later as Emperors, until the Russian Revolution of 1917. Peter the Great (reigned 1682 - 1725), a grandson of Michael Romanov, reorganized the Russian state along more Western lines, establishing the Russian Empire in 1721.
Document 5: Tsarevna Catherine Ivanovna of Russia: Tsarevna Catherine Ivanovna of Russia (20 October 1691 – 14 June 1733) was a daughter of Tsar Ivan V and Praskovia Saltykova, eldest sister of Empress Anna of Russia and niece of Peter the Great. By her marriage, she was a Duchess of Mecklenburg-Schwerin.
Document 6: Tsarevich Dmitry Ivanovich of Russia (1552–1553): Dmitri Ivanovich (; 11 October 155226 June 1553) was the first Tsarevich or Tsesarevich - the heir apparent - of the Tsardom of Russia, as the eldest son of Ivan the Terrible, or "Ivan IV of Russia" and his first Tsaritsa, Anastasia Romanovna. He was the third child and first son of the couple and died in infancy.
Document 7: Boston: On April 15, 2013, two Chechen Islamist brothers exploded two bombs near the finish line of the Boston Marathon, killing three people and injuring roughly 264.
Document 8: RAF-977: The RAF-977 was a Soviet cabover van made by Riga Autobus Factory (RAF) based on components from the GAZ-21 Volga. It was introduced in 1958 and was manufactured in two main styles: a 10-seater minibus and an ambulance. In 1961, an updated version called the RAF-977D was put into production; this had a one-piece windshield, instead of the split, and Volga steering wheel among its other detail changes. Variants included the 977I ambulance and a special "Intourist" model, which had better seats, roof lights, and sunroof.
Document 9: Russkaya Station: For the shore of Antarctica, the winds are considered to be rather strong. The average number of days per year with wind speeds of over in the area around the station is 264, and on 136 of those the wind speed is over . The average temperature in the coldest months of July–August is ; in the warmest months of December–January it is . The lowest temperature ever recorded at the station was in 1985, and the warmest was in 1983. The average overall temperature over the course of a year is , and the average amount of snowfall is around .
Document 10: Kotlyakovskoya Cemetery bombing: The Kotlyakovskoye Cemetery bombing was an attack on a funeral service in Moscow which killed fourteen people on November 11, 1996. The bombing, carried out via remote control, targeted members of an Afghan War veterans support group as well as their families. The victims were attending the funeral of Mikhail Lihodey, the former president of the veterans group who had been killed with his bodyguard in 1994.
Document 11: August 2004 Moscow Metro bombing: The official investigation concluded that it was organized by the same group as the February 2004 Moscow metro bombing, as well as two previous terrorist attacks on bus stops in Voronezh, southern Russia, in 2004. The deaths included the bomber and her accomplice, Nikolay Kipkeev (Kipkeyev), the head of an Islamic militant group Karachay Jamaat from the republic of Karachay–Cherkessia, as the bomb apparently exploded prematurely while the two were standing in the entrance hall of the metro station.
Document 12: Dmitry Borisovich: Dmitry Borisovich (; 11 September 1253, Rostov – 1294, Rostov) was a Russian nobleman. He was the eldest of the three sons of Prince Rostov Boris Vasylkovych from his marriage to Princess Maria Yaroslavna of Murom. He was Prince of Rostov (1278–1286 and 1288–1294) and Prince of Uglich (1285–1288).
Document 13: Climate of Moscow: Snow cover (averaging 3 -- 5 months per year) is formed at the beginning of November and melts in beginning of April, but in recent years snow cover has lasted shorter than usual. For example, in the winter of 2006 -- 2007 the snow cover did n't form until the end of January, and melted at the beginning of March; in 2007 -- 2008, the snow cover melted at the end of February, and in the 2008 -- 2009 winter, snow cover did n't form until the end of December, which is one month later than usual. Yet in 2011 - 2012 it melted in the middle of April.
Document 14: 81-740/741: 81-740/741 (Rusich, ), is a type of rolling stock specially designed for running under the harsh winter climate of outdoor Moscow. Rusich also features a corridor connection, allowing passenger access between two contiguous cars. They are currently assigned to the metro lines including Arbatsko-Pokrovskaya Line, Filyovskaya Line, Koltsevaya Line and Butovskaya Line of Moscow Metro, and all lines of the Sofia Metro in Bulgaria.
Document 15: Museum of the Moscow Railway (Paveletskaya station): The museum was formerly the Museum of Lenin’s funeral train. It still houses exhibits relating to Vladimir Lenin's Funeral train including the 4-6-0 steam locomotive U-127 (Russian У-127) and Lenin’s funeral van No 1691. The collection of exhibits has been expanded and it now also houses many artifacts concerning the Moscow Railway and the history of Russian Railways from the beginnings of the railways in Russia to the present day. The collection includes models, displays, documents, photographs, uniforms and items of railway equipment. U-127 is the only surviving Russian locomotive class U.
ground_truth: Anastasia Romanovna
sub_queries: 81-740/741 >> operator Answer: Moscow Metro
August 2004 Moscow Metro bombing >> country Answer: Russia
Tsarevich Ivan Ivanovich of Russia >> mother Answer: Anastasia Romanovna