A pollster took a random sample of 100 students from a large university and computed a 95% confidence interval to estimate the percentage of students who were planning to vote in the upcoming election. The pollster felt that the confidence interval was too wide to provide a precise estimate of the population parameter. What could the pollster have done to produce a narrower confidence interval ?
a. Increase the sample size to 150.
b. Increase the confidence level to 99%.
c. Both a and b
d. None of the above