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]: Coombs tests detect these bodies bound to erythrocytes, and a technique that uses these entities is ELISA. These molecules have a namesake fold, in which two beta sheets are held together by amino acid charges. These adaptable molecules can somatically recombine in a process called V(D)J recombination and are also capable of changing isotype by altering conformation of their heavy chains. Like enzymes, they operate via a a so-called "lock-and-key" mechanism, as verified by Linus Pauling. FTP, name these characteristically y-shaped immune molecules exploited in vaccination and produced by B cells in response to specific antigens.
[EX A]: Science

[EX Q]: This rule holds if the operator algebra for some set of observables is non-trivial; that is true because it is derived via the Schwarz inequality applied to the expectation value of the commutator of two observables operators. It formally bounds the product of the dispersions in two observables. An adapted form of this law applies to energy and time; it applies directly to any two components of spin, but it is best known in its application to position and momentum, the product of the standard deviations of which is at least h-bar over two. FTP, name this principle from quantum mechanics that limits the precision of measurements.
[EX A]: Science

[EX Q]: the hot chocolate effect, this quantity is reduced because of bubble density, which occurs due to the addition of fine powders to liquids. The mass specific total enthalpy in perfect gas compressible flow is equal to a term featuring this quantity squared multiplied by quantity one plus partial derivative of pressure with respect to energy multiplied by M squared, end quantity. For an ideal gas, this is given by the square root of the adiabatic index times pressure divided by density, and it is generally given by the square root of the bulk modulus divided by density. Generally approximated as 331 meters per second in dry air at 0 Celsius, the speed of an object divided by this quantity is known as the Mach number. For 10 points, name this quantity defined as the rate at which waves that transfer noise move through an elastic medium.
[EX A]:
Science