请教三道【GMAT OG 10th CR分类Lawyer版】里面的题目~！

zhaohaochen

13. 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.
E. Several federal government programs have been designed which will enable domestic machine-tool manufacturing firms to compete successfully with foreign toolmakers.

C是答案，这道题到底啥意思啊……


133. In 1960, 10 percent of every dollar paid in automobile insurance premiums went to pay costs arising from injuries incurred in car accidents. In 1990, 50 percent of every dollar paid in automobile insurance premiums went toward such costs, despite the fact that cars were much safer in 1990 than in 1960.
Which of the following, if true, best explains the discrepancy outlined above?
(A) There were fewer accidents in 1990 than in 1960.
(B) On average, people drove more slowly in 1990 than in 1960.
(C) Cars grew increasingly more expensive to repair over the period in question.
(D) The price of insurance increased more rapidly than the rate of inflation between 1960 and 1990.
(E) Health-care costs rose sharply between 1960 and 1990.

E是答案，可为啥C不行呢？

153. Technological improvements and reduced equipment costs have made converting solar energy directly into electricity far more cost-efficient in the last decade. However, the threshold of economic viability for solar power (that is, the price per barrel to which oil would have to rise in order for new solar power plants to be more economical than new oil-fired power plants) is unchanged at thirty-five dollars.

Which of the following, if true, does most to help explain why the increased cost-efficiency of solar power has not decreased its threshold of economic viability?

(A) The cost of oil has fallen dramatically.
(B) The reduction in the cost of solar power equipment has occurred despite increased raw material costs for that equipment.
(C) Technological changes have increased the efficiency of oil-fired power plants.
(D) Most electricity is generated by coal-fired or nuclear, rather than oil-fired, power plants.
(E) When the price of oil increases, reserves of oil not previously worth exploiting become economically viable.
C是答案，这题啥意思呢……？