Most People Can Roll Their Tongues, but Many People Can't

Multiple Choice

Most people can roll their tongues, but many people can't. Whether or not a person can roll his tongue is genetically determined. Suppose we are interested in determining what percentage of students can roll their tongues. We get a simple random sample of 400 students and find that 317 can roll their tongues. The margin of error for a 95% confidence interval for the true percentage of tongue-rollers among students is closest to

A) 0.04%.
B) 2.0%.
C) 3.0%.
D) 4.0%.
E) 20.75%.