The fundamental problem （ ） their inability to distinguish between reality and invention. A、is proportionate to B、is composed of C、lies in D、relies on 【正确答案】：C 【题目解析】：本题考查动词短语辨析。be proportionate to“成比例”， be composed of“由…构成”， lie in“在于”， rely on“依靠”。句意：最根本的问题在于他们无法分清现实和虚构。故选C。
