The coach of a college men's soccer team records the resting heart rates of the 27 team members. You should not trust a confidence interval for the mean resting heart rate of all male students at this college based on these data because
(a) with only 27 observations, the margin of error will be large.
(b) heart rates may not have a Normal distribution.
(c) the members of the soccer team can't be considered a random sample of all students.