单选题 Tebbut's own product, called Brainstorm, is a sophisticated software 'ideas organizer' that is cheap, easy to use and quite helpful.
【正确答案】 C
【答案解析】sophisticated“诡辨的、复杂的、久经世故的”；different“不同的”； excellent“卓越的、极好的”；complex“复杂的、合成的”；old“老的，年纪大的”。