Select the best answer. Which of the following statements about the sampling distribution of the sample mean is incorrect?

a) The standard deviation of the sampling distribution will decrease as the sample size increases.

b) The standard deviation of the sampling distribution is a measure of the variability of the sample mean among repeated samples.

c) The sample mean is an unbiased estimator of the population mean.

d) The sampling distribution shows how the sample mean will vary in repeated samples.

e) The sampling distribution shows how the sample was distributed around the sample mean.