Consumer advocate: In some countries, certain produce is routinely irradiated with gamma rays in order to extend shelf life. There are, however, good reasons to avoid irradiated foods. First, they are exposed to the radioactive substances that produce the gamma rays. Second, irradiation can reduce the vitamin content of fresh foods, leaving behind harmful chemical residues. Third, irradiation spawns unique radiolytic products that cause serious health problems, including cancer. Each of the following, if true, weakens the consumer advocate's argument EXCEPT: ['Unique radiolytic products have seldom been found in any irradiated food.', 'Cancer and other serious health problems have many causes that are unrelated to radioactive substances and gamma rays.', 'A study showed that irradiation leaves the vitamin content of virtually all fruits and vegetables unchanged.', 'A study showed that the cancer rate is no higher among people who eat irradiated food than among those who do not.']