$\begin{array}{1 1} (a)\;\overrightarrow{E} =\large\frac{1}{4\pi \in_0} \frac{p}{r^3} \hat p \\ (b)\;\overrightarrow{E} =\large\frac{1}{4\pi \in_0} \frac{p}{r^2} \hat p\\ (c)\;\overrightarrow{E} =\large\frac{1}{4\pi \in_0} \frac{2p}{r^3} \hat p \\(d)\;\overrightarrow{E} =\large\frac{1}{4\pi \in_0} \frac{p}{2r^3} \hat p \end{array} $