求助！Manhattan Chapter6 第五题的理解。

vi.len

Ethanol, a fuel derived from corn, can be used alone to power cars or along with gasoline to reduce the amount of gas consumed. Unlike gasolin, ethanol is easily renewable since it is primarily converted from the sun's energy. Moreover, compared with conventional gasoline, pure ethanol is a cleanser-buring fuel. To save energy and reduce pollution, many individuals advocated the increased usage of ethanol as a primary fuel source in conjunction with or in place of gasoline.
in evaluating the recommendation to increase the use of ethanol, it would be important to research all of the following EXCEPT:
(A) Whether the energy required to grow and pocess corn used as fuel is greater than the amount of energy ultimately produced.
(B) Whether more energy is saved when using ethanol in conjunction with or in place of gasoline.
(C) Whether ethanol is as efficient a fuel as gasoline
(D) Whether it is posiible to produce more ethanol than is currently produced
(E) Whether the process of growing corn for fuel would result in as much pollution as does the production of conventional gasoline.

OA:B

解释是：if more energy is saved using ethanol in conjunction with gasoline, then the conclusion holds. If more energy is saved using ethanol in place of gasoline, then the conclusion holds.
either way is a same thing.

可是我对B的理解是：能量是否可以被更多的保存，通过这两种方法。（通过这两种方法，MORE energy is saved or less energy is saved.）
答案对B的理解是：能量是否可以被更多的保存，通过这两种方法中的其中一种。（两种方法中的哪一种能保存更多能量）

我不知道我的理解哪里出现了问题。烦请大神指出来。