求教OG12 74

pansy

74. 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 Malvernian oil fi elds is increasing at a steady pace. If these trends in fuel production
and usage continue, therefore, Malvernian reliance on foreign sources for fuel is likely to decline soon.
Which of the following would it be most useful to establish in evaluating 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 proportion 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 existing oil-burning heating systems in Malvernia already been converted to natural-gas-burning
heating systems?

我选了E，感觉是不太对，但也说不出所以然。
正解为D，没看懂，求NN指点，