For a dataset $X = \{x_1, x_2, \dots, x_n\}$ with mean $\bar{x}$, let $S = \sum_{i=1}^n x_i^2$ be the sum of the squares of the values, and let $D = \sum_{i=1}^n (x_i - \bar{x})^2$ be the sum of the squared deviations from the mean. Which of the following equations correctly express the relationship between these quantities?