Those who use sunscreens most regularly are people who believe themselves to be most susceptible to skin cancer. Most people who purchase a sunscreen product will not purchase the most expensive brand available. Skin cancer generally develops among the very old as a result of sunburns experienced when very young. The development of sunscreens by pharmaceutical companies was based upon research conducted by dermatologists.
Researchers announced recently that over the past 25 years the incidence of skin cancer caused by exposure to harmful rays from the sun has continued to grow in spite of the increasingly widespread use of sunscreens. This shows that using sunscreen is unlikely to reduce a person' s risk of developing such skin cancer.
Which one of the following, if true, most weakens the argument?