The Point That Fights the Correlation

Samples $(x, y)$ are drawn from a bivariate Gaussian with mean at the origin and covariance matrix $\Sigma = \begin{pmatrix} 1 & -0.5 \\ -0.5 & 1 \end{pmatrix}$. Among the four observations below, which one would you flag as the strongest outlier? I. $(1, 0)$ II. $(1, -1)$ III. $(-1, -1)$ IV. $(0, 1)$