Find the equation of the circle with centre $(1,1)$ and radius $\sqrt 2$

Question

$\begin{array}{1 1} x^2 +y^2 - 2x-2y = 0\\ x^2 +y^2 - 2x+2y = 0 \\ x^2 +y^2 + 2x-2y = 0 \\ x^2 +y^2 + 2x+2y = 0 \end{array} $