单项选择题
Questions 22-26 Classify the. following groups of people according to whether they believe
A．Supplementation may have a positive effect. B．Supplementation may have a negative effect. C．Supplementation has no effect.
A．is ineffective in attacking free radicals. B．alerts the immune system to the presence of free radicals. C．attacks both free radicals and the immune system. D．prevents the immune system from responding to free radicals.