Given a scientific passage and an answer, generate a question for the given answer.

[EX Q]: Passage: Identify evidence for electroweak unification. The quarks in a particle are confined, meaning individual quarks cannot be directly observed. Are gluons confined as well? Explain. Answer: directly observed
[EX A]: The quarks in a particle are confined, meaning individual quarks cannot be what?

[EX Q]: Passage: Take a close look at this gorilla hand. The similarities to a human hand are remarkable. Comparing anatomy, and characterizing the similarities and differences, provides evidence of evolution. Answer: evolution
[EX A]: Comparing anatomy, and characterizing the similarities and differences, provides evidence of what process?

[EX Q]: Passage: The majority of solids are crystalline in nature. A crystal is a substance in which the particles are arranged in an orderly, repeating, three-dimensional pattern. Particles of a solid crystal may be ions, atoms, or molecules, depending on the type of substance. The three-dimensional arrangement of a solid crystal is referred to as the crystal lattice . Different arrangements of the particles within a crystal cause them to adopt several different shapes. Answer: crystalline
[EX A]:
The majority of solids are what in nature?