Soon comics were so prevalent as to attract the attention of serious critics.
【正确答案】 C
【答案解析】解析:形容词辨析。prevalent表:普遍的,流行的;而选项A.successful成功的;B.prosperous繁荣的;C.widespread分布广泛的,普遍的;D.persuasive善说服的;因此选项C为答案。