A random sample of 20 healthy adults eating a traditional American diet is selected. They agree to adopt a vegetarian diet for 1 month. Based on their 20 sample cholesterol change values, a 95% one-sample t confidence interval for the population mean change in blood cholesterol level after switching diet is reported as the interval -27.9 to -11.6 mg/dl. If we use a matched-pairs t confidence interval in some statistical software with the 20 sample cholesterol values at the beginning of the study and the 20 sample cholesterol values at the end of the study, the resulting 95% confidence interval;a) could be narrower or wider but we cannot tell until we get the software output. b) would be much narrower. c) would be slightly narrower. d) would be exactly the same. e) would be much wider. f) would be slightly wider.