pls solve

You and your friend are trying to find the point group of a molecule that is known to be chiral. You both identify two perpendicular C2 symmetry elements, and your friend immediately shouts "it's D2d !". Without even thinking much further, how do you know your friend must be wrong? You and your friend are trying to find the point group of a molecule, but you can't find any mirror planes. Your friend immediately says, "it must be chiral!" How should you correct your friend