You turn your Web browser to the online Harris Interactive Poll. Based on 2163 responses, the poll reports that 43% of U.S. adults said they would like to be richer, 21% said thinner, 14% said smarter, and 12% said younger. Nearly 1 in 10 (9%) said they would not want to choose any of the given options.7 You should refuse to calculate a 95% confidence interval for the proportion of all U.S. adults who would like to be richer based on this sample because
(a) the poll was taken a week ago.
(b) inference from a voluntary response sample can't be trusted.
(c) the sample is too large.