What is meant by the term "90% confident" when constructing a confidence interval for a mean? a. if we took repeated samples, approximately 90% of the samples would produce the same confidence interval. b. if we took repeated samples, approximately 90% of the confidence intervals calculated from those samples would contain the sample mean. c. if we took repeated samples, approximately 90% of the confidence intervals calculated from those samples would contain the true value of the population mean. d. if we took repeated samples, the sample mean would equal the population mean in approximately 90% of the samples?