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: sum of the squares of the reciprocals of this function evaluated at the nonnegative integers is equal to the modified Bessel function of the first kind at x=2. The Leviathan Number is found by evaluating this function at 10 to the 666th power. The rising type can be represented with the Pochhammer Symbol. Wilson's Theorem states that this function of any prime minus 1 is also congruent to -1 modulo that prime. Legendre's theorem provides a corollary to determine the number of (*) trailing zeroes of this function evaluated at nonnegative integers. When this function is evaluated at large numbers, Stirling's approximation is used. The gamma function extends this function to all complex numbers other than negative integers. For 10 points, name this function that, for positive integers n, is the product from 1 to n, and which is represented by an exclamation point.

Answer: Science


Question: Seas of calcite predominate during times of low concentration of this element. The NIMS probe discovered that Ganymede has a sulfate of this element, which is also used to treat eclampsia. Its molten form is used to make metallic titanium in the Kroll process. The active site of rubisco contains a carbamylated lysine attached to an ion of this element. Its cationic form is used to stabilize the product of PCR, and it is also prevalent in certain reagents in a Schlenck equilibrium. It is found in Grignard reagents as well as coordinated to the porphyrin ring of chlorophyll. For 10 points, name this element with atomic number 12 and symbol Mg.

Answer:
Science