If y1 , y2 are the ordinates of two points P and Q on the parabola and y3 is the ordinate of the point of intersection of tangents at P and Q, then
(a) y1 , y2 , y3 are in A.P.
(b) y1 , y3 , y2 are in A.P.
(c) y1 , y2 , y3 are in G.P.
(d) y1 , y3 , y2 are in G.P.