Normal drawn to `y^2=4a x` at the points where it is intersected by the line `y=m x+c` intersect at `P` . The foot of the another normal drawn to the parabola from the point `P` is (a)`(a/(m^2),-(2a)/m)` (b) `((9a)/m ,-(6a)/m)` (c)`(a m^2,-2a m)` (d) `((4a)/(m^2),-(4a)/m)`