The tangent and normal at `P(t)`, for all real positive `t`, to the parabola `y^2= 4ax` meet the axis of the parabola in `T` and `G` respectively, then the angle at which the tangent at `P` to the parabola is inclined to the tangent at `P` to the circle passing through the points `P, T `and `G` is
A. `tan^(-1)(t^(2))`
B. `cot^(-1))(t^(2))`
C. `tan^(-1)(t)`
D. `cot^(-1)(t)`
