C. why can the normal distribution be used in part (b), even though the sample size does not exceed 30? a. since the distribution is of sample means, not individuals, the distribution is a normal distribution for any sample size. b. since the mean pulse rate exceeds 30, the distribution of sample means is a normal distribution for any sample size. c. since the original population has a normal distribution, the distribution of sample means is a normal distribution for any sample size. d. since the distribution is of individuals, not sample means, the distribution is a normal distribution for any sample size.