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]: Paulo Ribenboim proved in 1991 that the set of these is Diophantine, and in 1912 Edmund Landau proposed four "unattackable problems" dealing with them, none of which have yet been solved. The theorem named for them states that the number of them less than or equal to n is approximately equal to n divided by the natural logarithm of n. The GIMPS project seeks to find examples of the Mersenne type of this number, ordinary examples of which can be found using the sieve of Eratosthenes. For 10 points, identify these numbers whose only two factors are 1 and itself.
[EX A]: Social Science

[EX Q]: This artist only completed the preparatory sketches for the epic Opening of the Doors of the Spanish Inquisition. This artist showed a cart stopped next to a gray building emitting white smoke in The Lime Kiln. He painted an unusual still-life of severed limbs called Anatomical Pieces, and he featured horses in his paintings Derby at Epsom and Horse Frightened By Lightning. A horse rearing away from an unseen attacker appears in his The Charging Chasseur. He studied bodies in the morgue of the Hospital Beaujon for his most famous work, which sees a man waving a red handkerchief on the top right and a bloody hatchet implies cannibalism. For 10 points, name this French Romantic painter of The Raft of the Medusa.
[EX A]: Fine Arts

[EX Q]: Materials with this property can exhibit a noise arising from self-organized criticality known as the Barkhausen effect. The Ising model was originally formulated to study this phenomenon, in which regions become separated by Bloch walls and materials exhibiting this property are frequently subject to hysteretic effects. The anti variety of this property disappears above the Neel point, while this property itself disappears above the Curie point, where the material transitions to paramagnetism. FTP, identify this form of magnetism resulting from the spontaneous alignment of domains, which is present in metals such as nickel and iron.
[EX A]:
Science