Assume that a Coke/Pepsi survey was conducted of 400 randomly chosen individuals from Gainesville. 200 people selected Coke. Which of the following statements correctly explains how the confidence interval for population proportion of people that prefer Coke should be computed?

A. There aren't 15 successes and 15 failures. A confidence interval can not be done.

B. There aren't 15 successes and 15 failures. A confidence interval can be computed by adding 2 successes and 2 failures.

C. There aren't 15 successes and 15 failures. A confidence interval can be computed by adding 4 successes and 5 failures.

D. There are at least 15 successes and 15 failures. A large sample confidence interval for population proportion can be computed (phat +/- z * sqrt(p*(1-p)/n) with no additional values added.