Let $O$ be the vertex and Q be any point on the parabola, $x^2=8y$ . If the point P divides the line segment OQ internally in the ratio $1:3$ , then the locus of P is :

Question

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