An electric dipole with dipole moment $5\times 10^{-6}\text{Cm}$ is aligned with the direction of a uniform electric field of magnitude $4\times 10^5\text{N/C}$. The dipole is then rotated through an angle of $60^{\circ }$ with respect to the electric field. The change in the potential energy of the dipole is:

1. A
   $0.8\text{J}$
2. B
   $1.0\text{J}$
3. C
   $1.2\text{J}$
4. D
   $1.5\text{J}$