Question: Strahlen (Rays) for a percussionist (vibraphone and/or glockenspiel) and ten-channel sound recording is a composition by which German composer, widely acknowledged by critics as one of the most important ; but also controversial composers of the 20th and early 21st centuries?
{'answer': 'Karlheinz Stockhausen', 'supporting_facts': [['Strahlen', 0], ['Karlheinz Stockhausen', 0]]}