Several teams of scientists performed the various experiments and all of the teams had similar results. To lessen the undesirable side effects of chemotherapy, the use of marijuana has been recommended for cancer patients who are free of the herpes virus. The carcinogenic effect of THC could be neutralized by the other ingredients found in marijuana. If chemists modify the structure of THC, THC can be safely incorporated into medications to prevent herpes.
An ingredient in marijuana known as THC has been found to inactivate herpes viruses in experiments. In previous experiments researchers found that inactivated herpes viruses can convert healthy cells into cancer cells. It can be concluded that the use of marijuana can cause cancer.
Which one of the following, if true, most seriously weakens the argument?