What system did arnold schoenberg invent to organize atonal composition?

He invented a system called Twelve-Tone Technique.

Arnold Schoeneberg was an Austrian-American composer and he is known for his innovations in atonality. Atonality is music that lacks a tonal central, also known as a key. A hierarchy of pitches focusing on a single, central note is not used and the notes function independently of one another.

The Twelve-Tone Technique is a way of ensuring that all the twelve notes on the chromatic scale are sounded as often as possible, without giving more importance to one particular note. The emphasis on one particular note is prevented by means of using tone rows.

The correct answer to this open question is the following.

Arnold Schoenberg invented the twelve-tone technique or twelve-tone serialism to organize the atonal composition. In this system, each tone is given equal importance.

Arnold Schoenberg (1874-1951) was an Austrian composer, naturalized American that created the 12-tone system of composition. It provided a new musical structure compared with old tonality. Instead of just using one or two tunes, Arnold Schoenberg used 12 tones for compositions. In the system, no note would predominated nor had a hierarchy in the composition. The basic set of notes was known as the 12-tone row. Other composers followed his new system such as Alban Berg and Igor Stravinsky.