Suppose the Statistics Department at TAMU wants to create a confidence interval for the proportion of students that get an A in Stat 303 this semester. In past semesters, the proportion has been around 0.30 (30%). The department wants an interval with a confidence level of 95% and a margin of error of 0.02. What sample size should they use?

A) It is impossible to determine. B) 798 C) 2017 D) 1557 E) 1121

Please give explanation why it is correct.