【正确答案】 C

【答案解析】句意：他是众所周知的著名歌手。be known for: 因…而闻名。be known to: (某对象)知道：The old city is known to the world. 全世界都知道这个城市。be known as: 作为…而闻名：He is known as the traitor. 他作为叛徒而闻名。