Quadrilaterals

If bisectors of ∠A and ∠B of a quadrilateral ABCD intersect each other at P, of
∠B and ∠C at Q, of ∠C and ∠D at R and of ∠D and ∠A at S, then PQRS is a
(A) rectangle (B) rhombus (C) parallelogram
(D) quadrilateral whose opposite angles are supplementary