The main component of green tea is tea polyphenols. Recently, a large number of animal experiments have found that tea polyphenols can inhibit the proliferation of tumor cells and promote the death of tumor cells. However, some experts have not found that the more tea is consumed, the more cancer The lower the incidence, they don't think regular drinking tea can prevent cancer. Which of the following, if true, is the most reasonable hypothesis for the expert to conclude? ['If tea is contaminated by carcinogens such as heavy metals, pesticides during production, processing, and transportation, the more tea you drink, the more you risk cancer.', 'If people drink tea for a long time but follow bad habits such as smoking, drinking, staying up late, etc. , it is difficult to see the anti-cancer effect of regular tea drinking.', 'Only by assuming that teas of different varieties but the same serving size contain basically the same tea polyphenols, can we conclude that regular tea drinking can prevent cancer.', 'Only when a large number of people drink tea is found that the incidence of cancer decreases, can we conclude that regular tea drinking can prevent cancer.']