Gaussian Distribution - Brainteaser

Consider the data (x, y) drawn from a Gaussian distribution centered at the origin with covariance matrix Σ = [1, −0.5; −0.5, 1]. Which data- point is most likely to be considered an outlier? I. \((1,0)\) II. \((1,-1)\) III. \((-1,-1)\) IV. \((0,1)\)