Vitacorp, a manufacturer, wishes to make its information booth at an industry convention more productive in terms of boosting sales. The booth offers information introducing the company's new products and services. To achieve the desired result, Vitacorp's marketing department will attempt to attract more people to the booth. The marketing director's first measure was to instruct each salesperson to call his or her five best customers and personally invite them to visit the booth.

Which of the following, if true, most strongly supports the prediction that the marketing director's first measure will contribute to meeting the goal of boosting sales?

(A) Vitacorp's salespeople routinely inform each important customer about new products and services as soon as the decision to launch them has been made.
(B) Many of Vitacorp's competitors have made plans for making their own information booths more productive in increasing sales.
(C) An information booth that is well attended tends to attract visitors who would not otherwise have attended the booth.
(D) Most of Vitacorp's best customers also have business dealings with Vitacorp's competitors.
(E) Vitacorp has fewer new products and services available this year than it had in previous years.

I choose the option D because the question states that which of the following, if true, most strongly supports the prediction that the marketing director's first measure will contribute to meeting the goal of boosting sales. I thought that D would best strengthen the first measure taken by the marketing director.
But the OA is C. According to the OA, it seems that the goal of boosting sales is strengthened.

Can anyone explain this question with proper reasoning.