请问一道36套最后一套的逻辑单题 第8题。

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8. That sales can be increased by the presence of sunlight
within a store has been shown by the experience of
the only Savefast department store with a large
skylight. The skylight allows sunlight into half of the
store, reducing the need for artificial light. The rest of
the store uses only artificial light. Since the store
opened two years ago, the departments on the sunlit
side have had substantially higher sales than the other
departments.  
Which of the following, if true, most strengthens the
argument?
(A) On particularly cloudy days, more artificial light
is used to illuminate the part of the store under
the skylight.
(B) When the store is open at night, the departments
in the part of the store under the skylight have
sales that are no higher than those of other
departments.
(C) Many customers purchase items from
departments in both parts of the store on a single
shopping trip.
(D) Besides the skylight, there are several significant
architectural differences between the two parts of
the store.
(E) The departments in the part of the store under the
skylight are the departments that generally have
the highest sales in other stores in the Savefast
chain.  

我的问题是这个题目的E选项为什么不是正确选项！？