An electric dipole of moment $\;\overrightarrow{P}\;$ is lying along a uniform electric field $\;\overrightarrow{E}\;$ The work done in relating the dipole by $\;90^{0}\;is$

Question

$(a)\;PE\qquad(b)\;\sqrt{2} PE\qquad(c)\;\large\frac{PE}{2}\qquad(d)\;2PE$