13. Defense Department analysts worry that the ability of the LACE>United StatesLACE> 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.
E. Several federal government programs have been designed which will enable domestic machine-tool manufacturing firms to compete successfully with foreign toolmakers.(C)
og的解释如下：
Since the size of the machine-tool manufacturing base presumably has implications in area beyond national security, one might find it surprising that the industry raised the security issue in its petition. C, the best answer, explains that the industry turned to this issue because others tended to be ineffective in efforts to obtain governmental protection.
提干没大看懂，og的解释也不明白，还有c选项的意思也没搞明白，那位NN 能解释一下呀！非常感谢！ | 
