Hoping to get information that would allow them to negotiate new rates with their advertisers, Natural Health magazine phoned a random sample of 600 subscribers. 64% of those polled said they use nutritional supplements. Which is true? I. The population of interest is the people who read this magazine. II. '64%' is not a statistic; it's the parameter of interest. III. This sampling design should provide the company with a reasonably accurate estimate of the percentage of all subscribers who use supplements.