请教一道逻辑题

shannashui

Defense Department analysts worry that the ability of the United States to wage a prolonged war would be seriously endangered if the machine-tool manufacturing base shinks further. Before the Defense Department publicly connected this security issue with the import quota issue, however, the machine-tool industry raised the national security issue in its petition for import quotas.

Which of the following, if true, contrubutes mostly to an explanation of the machine-tool industry's raising the issue above regarding national security?

A When the aricraft industries retooled, they provided a large amount of work   for tool builders.
B The Defense Department is only marginally concerned with the effects of foreign competition on the machine-tool industry.
C The machine-tool industry encountered difficulty in obtaining governmental protection against imports on grounds other than defense.
D A few weapons important for defense consist of parts that do not require extensive machining,
E Several federal government programs have been designed which will enable domestic machine-tool manufacturing firms to compete successfully with foreign toomakers.

答案是C。C中表达的到底是什么意思呢？看不明白！
谢谢赐教！

shannashui

哦，我明白了！多谢，多谢！

zyh79

在说明一下：国防部对于进口配额，是将其与国家防御相联系，
            机器工业在此之前提出，当让想的不是国家防御，而是自身生存。
国防部没有请愿，也不需要请愿。请愿的只有机器工业。

shannashui

原来是这样啊？那么国防部发出的关于进口配额的请愿是不是应该和机器工业的相反喽？

zyh79

别弄错了，机器工业就进口配额问题发出请愿，是要求进口配额，而不是反对进口配额

zyh79

进口配额就是限制进口，保护自己啊，呵呵。
on grounds以。。。为根据

shannashui

那么，在C中，on grands 的意思是什么？
另外，如果机器工业也就进口配额发出请愿，那么不是增大了自身的竞争压力吗？我就是不明白他们为什么要发出请愿？
不好意思，我有点胡涂，请赐教！

zyh79

c的意思是说：
    机器工业在获得政府保护抵制进口方面遇到困境，不过，他们不是从国家防御的角度去看的。言外之意，他们是从自身利益去考虑的。
    这就解释了原文最后一句：在国防部门提出进口配额问题之前，他们早已就此问题进行请愿，只是出发点不同。