The factors of $x^4+y^4 +x^2y^2$ are

Question

$\begin{array}{1 1} (x^2+y^2)(x^2+y^2 -xy) \\ (x^2+y^2) (x^2-y^2)\\ (x^2+y^2+xy)(x^2+y^2-xy) \\ Factorization \; Not \;possible \end{array} $