[求助]请教OG的test上的一道题，没有讨论

Following several years of declining advertising sales, the Greenville Times reorganized its advertising sales force. Before reorganization, the sales force was organizes geographically, with some sales repersentatives concentrating on city-center businesses and other concentrating an different outlying regions. The reorganization attempted to increase the sales representatives' knowledge of clients' businesses by having each sales representative deal with only one type of industry or of retailing. After the reorganization, revenue from advertising sales increased.

In assessing whether the improvement in advertising sales can properly be attributed to the reorganization, it would be the most helpful to find out which of the following ?

B   Has the circulation of the Greenville Times increased substantially in the last two years?

E   Among the advertisers in the Greenville Times,  are there more types of retail business or more types of industrial business?

正确答案为B,  OG中给的解释是说发行量增加同样会带来首日增加，所以评估一下，以排除他因。

可是我理解E评估的是有没有多了很多的retail business或者industrial business，这不正是重组中多改变的的东西吗？评估了这个结果不是最有用吗？

请赐教！

我找了很久都没有找到这道题的讨论版，如果有以前的讨论版，还希望可以提供给我！小女子在此谢过啦！

怎么没有回答呢？

各位大侠！急！

求救中！！！！！！！！！！！

请NN们指点迷津吧