In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

[Q]: What do you need to happen if you want the water in the water experiment to have a greater arc?, Context: Mach argued that, in effect, the water experiment in an otherwise empty universe would remain flat. But if another object were introduced into this universe, perhaps a distant star, there would now be something relative to which the bucket could be seen as rotating. The water inside the bucket could possibly have a slight curve. To account for the curve that we observe, an increase in the number of objects in the universe also increases the curvature in the water. Mach argued that the momentum of an object, whether angular or linear, exists as a result of the sum of the effects of other objects in the universe (Mach's Principle).
[A]: an increase in the number of objects in the universe

[Q]: What is the last place listed that engaged in the slave trade?, Context: The slave trade was engaged in by European state and non-state actors such as Great Britain, the Netherlands, Portugal and private companies, as well as various African states and non-state actors. With rising anti-slavery sentiment at home and changing economic realities, Great Britain outlawed the international slave trade in 1807. Following the Napoleonic Wars, Great Britain established the West Africa Squadron in an attempt to halt the international traffic in slaves. It stopped ships of other nations that were leaving the African coast with slaves; the seized slaves were taken to Freetown, a colony in West Africa originally established for the resettlement of freed slaves from Britain. Britain intervened in the Lagos Kingship power struggle by bombarding Lagos in 1851, deposing the slave trade friendly Oba Kosoko, helping to install the amenable Oba Akitoye, and signing the Treaty between Great Britain and Lagos on 1 January 1852. Britain annexed Lagos as a Crown Colony in August 1861 with the Lagos Treaty of Cession. British missionaries expanded their operations and travelled further inland. In 1864, Samuel Ajayi Crowther became the first African bishop of the Anglican Church.
[A]: various African states

[Q]: When was the second time Mongols invaded Europe?, Context: During the early High Middle Ages, Germany was ruled by the Ottonian dynasty, which struggled to control the powerful dukes ruling over territorial duchies tracing back to the Migration period. In 1024, they were replaced by the Salian dynasty, who famously clashed with the papacy under Emperor Henry IV (r. 10841105) over church appointments as part of the Investiture Controversy. His successors continued to struggle against the papacy as well as the German nobility. A period of instability followed the death of Emperor Henry V (r. 111125), who died without heirs, until Frederick I Barbarossa (r. 115590) took the imperial throne. Although he ruled effectively, the basic problems remained, and his successors continued to struggle into the 13th century. Barbarossa's grandson Frederick II (r. 12201250), who was also heir to the throne of Sicily through his mother, clashed repeatedly with the papacy. His court was famous for its scholars and he was often accused of heresy. He and his successors faced many difficulties, including the invasion of the Mongols into Europe in the mid-13th century. Mongols first shattered the Kievan Rus' principalities and then invaded Eastern Europe in 1241, 1259, and 1287.
[A]:
1259