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.

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.
Science

One of this man's theories was supported by the discovery that Hittite contained forms in which distinct reflexes of the laryngeals are recorded, and he explained how the vowel alternations of a came about in his first work, Memoir on the Original System of Vowels in the Indo-European Languages. He is noted for his terms langue, or regularities and patterns in speech, and parole, or actual acts of speech. The work he is most famous for is often considered the foundation for structural linguistics, though Charles Bally and Albert Sechehaye actually published it. FTP name this Swiss linguist whose lecture notes and other materials were posthumously turned into the seminal Course in General Linguistics.
Social Science

This country's President Jorge Pacheco began to use torture techniques in response to labor  uprisings, leading to the rise of the Tupamaro movement. This country's victory at the Battle of Las  Piedras helped secure its independence from Spain, and its forces were led by national hero Jose (*)  Artigas at that battle. A civil war in this country saw one side supported by another country's dictator  Juan Manuel de Rosas until the intervention of Justo Jose de Urquiza, and that war in this country  involved the liberal forces of Fructuoso Rivera squaring off against Manuel Oribe, who led the Blancos. That same civil war in this country involved Giuseppe Garibaldi, who led its navy. For 10 points, name  this South American country located on the north bank of the Rio de la Plata.

History