单选题 He was so convinced that people were driven by ______ motives that he could not believe that anyone could be unselfish.

【正确答案】 C

【答案解析】(ulterior隐蔽的，秘而不宣的)。句意为；他深信人们受隐秘动机的驱使，因此，他不相信人们会大公无私。A．selfless无私的；B．personal 个人的，私人的；D．intrinsic 内在的，固有的。