单选题 Because the process of freezing food consumes energy, many people keep their electric freezers half-empty, using them only to store commercially frozen foods. Yet freezers that are half-empty often consume more energy than they would if they were kept fully stocked.
Which of the following, if true, contributes most to an explanation of the apparent discrepancy described above?

A、 A given volume of air in a freezer requires much more energy to be maintained at a temperature below freezing than does an identical volume of frozen food.
B、 The more often a freezer's door is opened, the more energy is required to maintain that freezer's normal temperature.
C、 When unfrozen foods are placed in a freezer, the average temperature of a given volume of air inside that freezer rises temporarily.
D、 A person who normally maintains a half-empty freezer can cut energy costs considerably by using a freezer that is 50 percent smaller.
E、 (E) An electric freezer can operate efficiently only if chilled air is free to circulate within the freezing compartment.

【正确答案】 A

【答案解析】[解析] 本题让我们解释the apparent discrepancy：半空的电冰箱比装满的电冰箱耗能更多，并且要解释双方的矛盾点或差异点是“energy”。因此，我们用关键词“energy”来定位选项，排除了(C)、(E)；若一定体积的空气维持于某一温度比相同体积的食物耗能更多，如(A)所述，那么就解释了上面的“discrepancy”，因此(A)正确；(B)不能说明“半空状态为什么耗能更多”；(D)只能说明电冰箱如何才能有效运行，不能解释“半空状态为什么耗能更多”，所以(D)不正确。