求教OG12上CR74题

In the past the country of Malvernia has relied heavily on imported oil. Malvernia recently implemented a program to convert heating systems from oil to natural gas. Malvernia currently produces more natural gas each year than it uses, and oil production in Malvernia fields is increasing at a steaty pace. If these trends in fuel production and usage continue, therefore, Malvernian reliance on foreign sources for fuel is likely to decilne soon,

Which of the following would it be most useful to establish in evaluatiing the argument？

A. When, if ever, will production of oil in Malvernia outstrip production of natural gas?

B.Is Malvernia among the countries that rely most on imported oil?

C.What propotion of Malvernia's total energy needs is met by hydroelectric, solar, and nuclear power?

D.Is the amount of oil used each year in Malvernia for generating electricity and fuel for transportation increasing?

E.Have any exsiting oil-burning heating systems in Malvernia already already been converted to natural gas-burning heating system?

OG的答案是D，但是怎么看都觉得D和结论无关，transportation在原文中并没有提到啊，求各位指点

噢，我理解了~

这里相当于引入了heating System以外的又一种消耗transportation来判断消耗的多少，多谢~  ：）