Which 19th century art movement most directly influenced the development of abstract art in the 20th century?

Which group of barbarian invaders at one time controlled part of italy and formed a kingdom in southern france, and were forced into spain by the franks?

Which style of polyphony uses a borrowed chant and arranges several new melodies and texts above and unrelated to the chant?

What is a principle of design that repeats elements to create good visual flow?