请教LSAT第一册P39的第4题/LSAT-15-4-6

Cathelin

LSAT第一册P39的第4题题目如下
Dried grass clippings mixed into garden soil gradually decompose,providing nutrients for beneficil soil bacteria .This rsults in better-than-average plant growth.Yet mixing fresh grass clippings into garden soil usually causes poorer-than-average pland growth.
Which one of the following,if true,most helps to explain the difference  in plant growth described above?
C)Some dried grass clipplings retain nutrients originally derived from commercial lawn fertilizers,and thus provide additional enrichment to the soil.
D)Fresh grass clipplings retain nutrients originally derived from commercial lawn fertilizers and  thus provide additional enrichment to the soil.
答案是D我认为应该是C吧？请教大家了，谢谢！

weiyu

C说有的干草有多的营养，你不能保证这个study中的干草不在其中．D说只有新鲜草才有多营养，正好解释了．

weiyu

I am glad to accept your comments and correction. Nothing could be true forever. Thanks for your comments again, host pumpkin.

Cathelin

感谢斑竹的教导，我真是汗颜啊！想想自己也真是笨啊，学计算机的怎么连个最基本的复制粘贴都不会。。。。我是笨到家了，没治了！！！

zj1983

这道题我也做错了！现在恍然大悟！