If two opposite angles of a quadrilateral
are supplementary, is the quadrilateral a
parallelogram?
A) No, because in parallelograms, angles
are supplementary if and only if they are consecutive.
B) No, because opposite angles in a parallelogram are never congruent.
C) Yes, but only when the angles of the quadrilateral are right angles.
Otherwise, it will be a trapezoid rather than a parallelogram.
D) Yes, because only squares have that property, and squares are both
parallelograms and quadrilaterals.