The Sample Variance $s ^ { 2 }$ Is an Unbiased Estimator of the Population Variance

Multiple Choice

The sample variance $s ^ { 2 }$ is an unbiased estimator of the population variance $\sigma ^ { 2 }$ when the denominator of $s ^ { 2 }$ is:

A) n.
B) n - 1.
C) n.
D) n + 1.