Although Many Active Ingredients Are Present in Over-The-Counter Oral Rinses

Although many active ingredients are present in over-the-counter oral rinses and dentifrices,very few have received the ADA Seal of Acceptance because of which of the following reasons?

A) The product has demonstrated reductions in plaque and gingivitis in short-term studies.
B) The product has been demonstrated efficacious only in in vitro studies.
C) The product has shown plaque reductions but not gingivitis reductions.
D) All of the above are correct.