Let a set of measured data be expressed by vector x = [x1, x2, x3, · · · , xn]T. Choose the right one in the following statements.
A、m = mean(x) can be used to evaluate the sample mean.
B、s2 = std(x) can be used to evaluate the sample variance.
C、s = var(x) can be used to evaluate the standard deviation.
D、m1 = median(x) can be used to evaluate the median value.