If the normal to a parabola $y^2=4ax$ make an angle $\theta$ with the axis and $\phi$ is the angle it makes when it cut the parabola again find the relation between $\theta$ & $\phi$?

Question

$\begin{array}{1 1}(a)\;\tan \phi=\large\frac{\tan \theta}{2}\\(b)\;\tan \phi=\large\frac{\tan \theta}{4}\\(c)\;\tan 2\phi=\large\frac{\tan \theta}{2}\\(d)\;4\tan \phi=\large\frac{\tan \theta}{2}\end{array}$