We Have Calculated a 95% Confidence Interval and Would Like

We have calculated a 95% confidence interval and would like our next confidence interval to have a smaller margin of error without losing any confidence. In order to do this, we can
I. change the z* value to a smaller number
II. take a larger sample
III. take a smaller sample

A) I only
B) II only
C) III only
D) I and II
E) I and III