请教一道比较，，，大家来看下

chaomat1988

There is a widespread belief in theUnited States and Western Europe that young people have a

smaller commitment to work and a careerthan their parents and grandparents and that the source

of the change lies in the collapse of the"work ethic."

(A) a smaller commitment to work and acareer than their parents and grandparents

(B) less of a commitment to work and a careerthan their parents and grandparents

(C) a smaller commitment to work and acareer than that of their parents and grandparents

(D) less of a commitment to work and acareer than their parents and grandparents had

答案是D，解释说是2个句子的比较，， 我选了C为什么 COMMITMENT的比较不可以呀？  前半句SMALLER COMMITMENT和后半句的 PARENTS和GRANDPARENTS的 COMMITMENT比较

chaomat1988

谢谢大神解释

rylstar01

个人觉得，在划线部分中出现了than，然后找划线部分的平行结构。
句中... young people have...than their parents and grandparents had...形成一个平行结构，即现在的年轻人的工作认同感与过去的他们的父辈和祖辈的工作认同感进行比较。如果没有had的话，则是现在的年轻人工作认同感与他们的父辈和祖辈比。这就显得不符合逻辑。
对于C选项的话，我同意楼上版主的。

aeoluseros

smaller commitment不对. smaller用于形容amout/size/importance，而less用于修饰程度，所以应该用less.
对于比较，C里面that有指代歧义，相比来讲，D更为清晰，而且gmat偏向于平行，即前后都是主谓结构。