参考答案

正确答案：C
解析：本题为细节题。要确定在记忆力衰退的问题上，年轻人与老年人的主要区别是什么。根据文章第五段“But she says that people in their twenties and thirties are losing memory at the same rate as people in their sixties and seventies．(但是她说人类记忆力衰退在其二、三十岁时和其六、七十岁时的速度是一样的。)”可以排除选项A．they lose their memory at a slowerrate；根据文章第四段的“…because their brains have more information than they need．”可以看出选项B．their brains can store much more information是不正确的，因为不是能够储存得更多，而是多到不需要的地步。从文章倒数第二段的“The study has found that older adults are more likely to remember false information as being true．”可以看出选项D．they are more likely to remember false information是老年人的问题，而不是青年人的问题。文章第一段的“Peopleyounger than thirty usually do not know that they are starting to forget information．”与选项C．they rarely realize they have memory problems一致，说明年轻人意识不到自己记忆力的减退。所以选项C是正确答案。