求解一道OG语法分册的题目！

elginlv

（题号20）Declining values for farm equipment and land,the collateral against which farmers borrow to get through the harvest season, is going to force many lenders to tighten or deny credit this spring.

(A)the collateral against which farmers borrow to get through the harvest season, is
(B)which farmers use as collateral to borrow against to get through the harvest season, is
(C)the collateral which is borrowed against by farmers to get through the harvest season, is
(D)which farmers use as collateral to borrow against to get through the harvest season, are
(E)the collateral against which farmers borrow to get through the harvest season, are

正确答案：E。我的问题是不知为何D错误。官方解释就简单的一句awkward and illogical。

kimfeng

如果D的话谁来做declining 的逻辑主语啊？