Which of the following explains why it is necessary to make a correction to the formula for sample variance?

a. If sample variance is computed by dividing by n, instead of n 2 1, the resulting values will tend to underestimate the population variance.

b. If sample variance is computed by dividing by n, instead of n 2 1, the resulting values will tend to overestimate the population variance.

c. If sample variance is computed by dividing by n 2 1, instead of n, the resulting values will tend to underestimate the population variance.

d. If sample variance is computed by dividing by n 2 1, instead of n, the resulting values will tend to underestimate the population variance.