[逻辑小分队] 大全-Ⅰ-18

大全-Ⅰ-18.    Critics of sales seminars run by outsideconsultants point out that since 1987, revenues of vacuum cleaner companieswhose employees attended consultant-led seminars were lower than revenues ofvacuum cleaner companies whose employees did not attend such seminars. Thecritics charge that for vacuum cleaner companies, the sales seminars are illconceived and a waste of money.

Whichof the following, if true, is the most effective challenge to the critics ofsales seminars?

(A) Those vacuum cleaner companies whosesales were highest prior to 1987 are the only companies that did not sendemployees to the seminars.

(B) Vacuum cleaner companies that havesent employees to sales seminars since 1987 experienced a greater drop in salesthan they had prior to 1987.

(C) The cost of vacuum cleaner salesseminars run by outside consultants has risen dramatically since 1987.

(D) The poor design of vacuum cleanersales seminars is not the only reason for their ineffectiveness.（A）

(E) Since 1987, sales of vacuum cleanershave risen twenty percent.

原题的意思是指the sales seminars没用。但A里说这个公司是唯一没用the sales seminars的但却有最高的销售额，说明the sales seminars确实没用，是支持原文的。为什么答案还是A啊？求高手解释。。