In a random sample of 40 people who rode a roller coaster one day, the mean wait time is 52.4 minutes with a standard deviation of 9.5 minutes.

In a random sample of 50 people who rode a Ferris wheel the same day, the mean wait time is 14.1 minutes with a standard deviation of 2.3 minutes.

Which interval is the 99% confidence interval for the difference between the mean wait times of everyone who rode both rides?

a. (34.3, 42.3)

b. (36.8, 39.8)

c. (35.8, 40.8)

d. (36.9, 40.7)