Derive an expression for the electric field at any point on the axial line of an electric dipole&nbs

Question

$\begin{array}{1 1} (a)\;E_{axial}=\large \frac{1}{4\pi \in_0} \frac{2p^2}{r(r^2-a^2)^2}\\ (b)\;E_{axial}=\large \frac{1}{4\pi \in_0} \frac{2pr}{(r^2-a^2)^2} \\ (c)\;E_{axial}=\large \frac{1}{4\pi \in_0} \frac{pr}{(r^2+a^2)^2} \\(d)\;E_{axial}=\large \frac{1}{4\pi \in_0} \frac{p}{(r^2+a^2)^2} \end{array} $