Question: Who is the mother of Tsarevich Ivan Ivanovich, of the country that experienced the August 2004 bombing of the transit system that includes the Metro-2?

full_context: Document 1: 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 2: Metro-2: Metro-2 () is the informal name for a purported secret underground metro system which parallels the public Moscow Metro (known as Metro-1 when in comparison with Metro-2). The system was supposedly built, or at least started, during the time of Joseph Stalin and was codenamed D-6 (Д-6) by the KGB. It is supposedly still operated by the Main Directorate of Special Programmes and Ministry of Defence.
Document 3: 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 4: 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 5: 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 6: 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 7: 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 8: List of metro systems: This list of metro systems includes electrified rapid transit train systems worldwide. In some cases, metro systems are referred to as subways, U-Bahns or undergrounds. As of October 2014, 157 cities in 55 countries around the world host the approximately 160 metro systems that are listed here. The London Underground first opened as an ``underground railway ''in 1863 and its first electrified underground line opened in 1890, making it the world's first metro system. The metro system with the longest route length is the Shanghai Metro; the busiest one is the Beijing Subway; and the one with the most stations is the New York City Subway.
Document 9: 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 10: New Delhi: Delhi Metro is being built and operated by the Delhi Metro Rail Corporation Limited (DMRC), a state-owned company with equal equity participation from Government of India and Government of National Capital Territory of Delhi. However, the organisation is under administrative control of Ministry of Urban Development, Government of India. Besides construction and operation of Delhi metro, DMRC is also involved in the planning and implementation of metro rail, monorail and high-speed rail projects in India and providing consultancy services to other metro projects in the country as well as abroad. The Delhi Metro project was spearheaded by Padma Vibhushan E. Sreedharan, the Managing Director of DMRC and popularly known as the "Metro Man" of India. He famously resigned from DMRC, taking moral responsibility for a metro bridge collapse which took five lives. Sreedharan was awarded with the prestigious Legion of Honour by the French Government for his contribution to Delhi Metro.
Document 11: 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 12: Dnipro Metro: The Dnipro Metro (; ) is a single-line rapid transit system that serves the city of Dnipro, the fourth largest city in Ukraine by population. The metro was the third system constructed in Ukraine, after the Kiev and Kharkiv metro systems, respectively, when it opened on December 29, 1995. The metro was the fourteenth built in the former Soviet Union region, and the first to open after the collapse of the Soviet Union in 1991.
Document 13: 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 14: 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 15: New Delhi: The Delhi Metro is a rapid transit system serving New Delhi, Delhi, Gurgaon, Faridabad, Noida, and Ghaziabad in the National Capital Region of India. Delhi Metro is the world's 12th largest metro system in terms of length. Delhi Metro was India's first modern public transportation system, which had revolutionised travel by providing a fast, reliable, safe, and comfortable means of transport. The network consists of six lines with a total length of 189.63 kilometres (117.83 miles) with 142 stations, of which 35 are underground, five are at-grade, and the remainder are elevated. All stations have escalators, elevators, and tactile tiles to guide the visually impaired from station entrances to trains. It has a combination of elevated, at-grade, and underground lines, and uses both broad gauge and standard gauge rolling stock. Four types of rolling stock are used: Mitsubishi-ROTEM Broad gauge, Bombardier MOVIA, Mitsubishi-ROTEM Standard gauge, and CAF Beasain Standard gauge.
ground_truth: Anastasia Romanovna
sub_queries: Metro-2 >> part of Answer: Moscow Metro
August 2004 Moscow Metro bombing >> country Answer: Russia
Tsarevich Ivan Ivanovich of Russia >> mother Answer: Anastasia Romanovna