If $st = 1$, then the tangent at $P$ and the normal at $S$ to the parabola meet at a point whose ordinate is (A) $\frac{(t^2+1)^2}{2t^3}$ (B) $\frac{a(t^2+1)^2}{2t^3}$ (C) $\frac{a(t^2+1)^2}{t^3}$ (D) $\frac{a(t^2+2)^2}{t^3}$
If $st = 1$, then the tangent at $P$ and the normal at $S$ to the parabola meet at a point whose ordinate is\\
(A) $\frac{(t^2+1)^2}{2t^3}$\\
(B) $\frac{a(t^2+1)^2}{2t^3}$\\
(C) $\frac{a(t^2+1)^2}{t^3}$\\
(D) $\frac{a(t^2+2)^2}{t^3}$