Does taking vitamin D increase the mean life span of a rat? A sample of 20 rats was randomized to group 1 (control) and group 2 jvitamin D). The life span (days) of each rat was measured. Given is some of the output. Which statement is correct? 0 Because 10 rats were randomized to each of the two groups, a matched pairs design could be used. 0 The standard errors estimate how much the average life spans for each group could vary if new samples of 10 rats were taken. The standard errors are only an estimate, not a measure for the variation in the averages for groups of 10 rats. 0 Because the two standard deviations are about equal, there is no evidence that the average life spans are different 0 About 95% of rats in group 1 have life spans between 470 days and 590 days