Important Research into the Persuasion Effects of Event Sponsorship Has

Important research into the persuasion effects of event sponsorship has uncovered all of the following recommendations EXCEPT:

A) Sponsorship content should be "visible", so that participants are aware of the sponsoring brand.
B) Event sponsorships are deemed ineffective if there is no mechanism for product sales.
C) The sponsorship should offer true value to the audience.
D) Planners should avoid multiple-sponsor events.