Mean and Variance Are Two Statistics Defined for Both the Population

Mean and variance are two statistics defined for both the population and the sample. What is the difference?

A) The value of the sample mean/variance varies from sample to sample, whereas there is just one value for the population mean/variance.
B) The value of the population mean/variance varies from sample to sample, whereas there is just one value for the sample mean/variance.
C) The value of the sample mean/variance is always less than the value of the population mean/variance, since the sample size is less than the population size.