From the Standard Deviation Formula, S² ⁼ $\frac{\sum_{i=1}^{n}(x-\bar{x})^{2}}{N}$ , Identify the Estimator

From the standard deviation formula, s² ⁼ $\frac{\sum_{i=1}^{n}(x-\bar{x}) ^{2}}{N}$
, identify the estimator.

A) $s^{2}$

B) $\sum_{i=1}^{n}$

C) $(x-\bar{x}) ^{2}$

D) $n-1$