While Many Active Ingredients Are Available Within Commercially Available Oral

While many active ingredients are available within commercially available oral rinses and dentifrices very few have received the ADA seal of therapeutic efficacy because of all of the following factors except:

A) product has only demonstrated reductions in plaque and gingivitis in short-term studies.
B) product has only been demonstrated efficacious in in vitro studies.
C) insufficient number of long-term studies demonstrating efficacy of product.
D) product has demonstrated efficacy but researchers had disclosed a conflict of interest.