A

The electric potential $V$ due to an electric dipole at a point in space is given by the equation:
$$ V = \frac{k(\mathbf{p} \cdot \mathbf{r})}{r^3} $$
where $k$ is a constant, $\mathbf{p}$ is the dipole moment vector, and $\mathbf{r}$ is the position vector from the dipole to the point. The negative sign is due to the potential being measured from a reference point, typically at infinity where potential is taken as zero. Therefore, option A represents the correct formula for the electric potential due to an electric dipole.