Find the axis,vertex,focus & equation of directix for the parabola $y^2=4ax$?

$\begin{array}{1 1}(a)\;y=0,(0,0),(9,0),x+a=0\\(b)\;x=0,(0,1),(8,0),x+2a=0\\(c)\;y=0,(0,1),(9,0),x^2+a=0\\(d)\;y=3,(3,0),(0,9),x^3+2a=0\end{array}$

Equation of axis is y=0
Vertex (0,0) (it is intersection axis & parabola)
Focus (9,0)
Equation of directix $x+a=0$
Directix is perpendicular to the axis.
Hence (a) is the correct answer.