The normal at the point `P(ap^2, 2ap)` meets the parabola `y^2= 4ax` again at `Q(aq^2, 2aq)` such that the lines joining the origin to P and Q are at right angle. Then (A) `p^2=2` (B) `q^2=2` (C) `p=2q` (D) `q=2p`