求教一道逻辑题

kaisyhu

“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 shrinks 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, contributes most to an explanation of the machine-tool industry’s raising the issue above regarding national security?

A. When the aircraft industries retooled, they provided a large amount of work for too 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.C

E. Several federal government programs have been designed which will enable domestic machine-tool manufacturing firms to compete successfully with foreign toolmakers
实在不懂C说的是什么意思，麻烦各位帮我解答一下，谢谢！！！

Which of the following, if true, contributes most to an explanation of the machine-tool industry’s raising the issue above regarding national security?

A. When the aircraft industries retooled, they provided a large amount of work for too 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.C

E. Several federal government programs have been designed which will enable domestic machine-tool manufacturing firms to compete successfully with foreign toolmakers
实在不懂C说的是什么意思，麻烦各位帮我解答一下，谢谢！！！