A researcher calculates confidence intervals at different confidence levels using the same sample data. Which of the following statements accurately describes the effect of increasing the confidence level while keeping all other factors constant? Select one: a. Increasing the confidence level decreases the width of the confidence interval. b. Increasing the confidence level increases the width of the confidence interval. c. Increasing the confidence level makes the confidence interval infinitely wide. d. Increasing the confidence level does not affect the width of the confidence interval