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.

[EX Q]: 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.
[EX A]: Science

[EX Q]: The column of Bertin is located in this organ, which is surrounded by a fascia named for Gerota. Children may experience minimal change disease in this organ. Collagen disorders like Alport Syndrome and Goodpasture's Syndrome affect this organ's basement membrane, and it's also the site of Wilms' tumors. This organ and the liver are the site of gluconeogenesis. The GFR is a measurement of its function. This organ falls into the pelvis in a condition which causes it to "float". Calcitriol and erythropoietin are synthesized by this organ, which secretes renin to increase blood pressure. Bowman's capsule surrounds this organ's glomerulus, and countercurrent exchange in its loop of Henle improves its filtration effficiency. For 10 points, name this paired organ composed of nephrons.
[EX A]: Science

[EX Q]: A quartet of these instruments respond to the trumpet's five-note query in Ives' The Unanswered Question. 19th century orchestras used the conical-bore Meyer version of this instrument, which was created as a reaction to a system created by Theobald Boehm. A physical property of platinum lends its name to Varese's work for this instrument titled Density 21.5. Walter Piston wrote a ballet about an "Incredible" player of this instrument, and Vivaldi wrote the concerti La Notte and Il Gardelino for it. Contemporary musicians who play this instrument include Jean Pierre Rampal and James Galway. For 10 points, name this woodwind instrument whose diminutive relative is the piccolo.
[EX A]:
Fine Arts