Final answer:
Arnold Schoenberg is the composer primarily associated with the creation of the twelve-tone system and serialism, which marked a significant move away from traditional tonal music towards atonality in the early 20th century.
Step-by-step explanation:
The main answer to the question 'The serialism and twelve-tone system were primarily created by what composer?' is C) Arnold Schoenberg. The twelve-tone system, also known as dodecaphony, is a method of musical composition devised by Austrian composer Arnold Schoenberg. This method of composition uses a series of all twelve notes in the chromatic scale, arranged in a particular sequence called a tone row. This tone row can then be manipulated through inversion, retrograde, and retrograde inversion, but all twelve notes must be used before any note can be repeated. This approach ensures that no single note has dominance over the others, effectively avoiding any sense of a traditional tonic or home key, which was typical in earlier Western music.The twelve-tone technique was a radical departure from the tonality that had dominated Western classical music since the Renaissance. Composer Arnold Schoenberg developed this system in the early 1920s as a way to explore new musical possibilities and to extend the principles of serialism beyond those used by his predecessors and contemporaries. While Beethoven, Schumann, and others from the Romantic era had pushed the boundaries of musical harmony, Schoenberg's approach was much more revolutionary.In conclusion, Arnold Schoenberg was a pivotal figure in the transition from romantic to atonal and serialist music. His twelve-tone system was a groundbreaking contribution to modern music, allowing for a new kind of musical structure and expression.