In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
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Question: A maximum independent set for this data structure can be found in linear time by adding alternating levels. In this structure, any two vertices or nodes must be connected by a single simple path, and thus it is connected and acyclic. By using (*) union-find with disjoint sets, one type of this structure containing all the vertices of a connected graph can be constructed. One variety of this data structure can be used to easily implement a binary search. This structure also comes in red-black and self-balancing-binary varieties. For 10 points, identify this data structure from computer science, a hierarchical graph in which "leaf" nodes ultimately flow from a "root" node.

Answer: Science


Question: Halogen addition to them creates a mixture of a 1-2 and 1-4 addition product. One preparation of them involves butane undergoing thermal dehydration. Another synthesis of the conjugated variety of this chemical group involves elimination of unsaturated alcohols and alkyl halides. They include a number of useful reagents, including ones named for Chan, Dane, Brassard, Rawal, and Danishefsky. In addition to the conjugated variety, they also occur in isolated and cumulated varieties. Conjugation energy guarantees that the conjugated form is the most stable. For ten points, what is this organic functional group whose 1,3 variety are a principal reactant in the Diels-Alder reaction, and which is characterized by a pair of double bonds.

Answer: Science


Question: During this battle, a bayonet charge by the 20th Maine, led by Joshua Chamberlain, helped defend one important hill. Besides Little Round Top, other areas of contest included Devil's Den and the Peach Orchard. The decisive action in this battle was a failed assault on Cemetery Ridge known as Pickett's Charge. For 10 points, name this Union victory after which Abraham Lincoln gave a namesake "address."

Answer:
History