Answer
Circle with equation $x^2+y^2=4$ in the $z=-2$ plane.
Work Step by Step
Here, the points are the intersection between the equation of cylinder $x^2+y^2=4$ and the plane $z=0$.
The set of points that satisfies such equations has the equation of a circle lying in the xy plane, centered at origin $O$, having a circle of radius $2$ and shifted two points down from the xy plane.
