Problem: A quadrilateral is inscribed in a parabola, then
(A) Quadrilateral may be cyclic.
(B) Diagonals of the quadrilateral may be equal.
(C) All possible pairs of adjacent side may be perpendicular.
(D) None of the above $\quad$ $\blacksquare$
Option (A) can be verified easily. I think both (B) and (C) are the criterion for rectangle, but I am unable to prove or disprove options (B) and (C). Please help.