A 95% confidence interval for the average salary of all CEOs in the electronics industry was constructed using the results of a random survey of 40 CEOs. The interval was ($99,752, $113,359) . To make more useful inferences from the data, it is desired to reduce the width of the confidence interval. Which of the following will result in an increased interval width?
a. Increase the sample size.
b. Decrease the level of confidence.
c. Both a and b.
d. Neither a nor b.