The potential $($relative to infinity$)$ at the midpoint of a square is $3\mathrm{.}0$ V when a point charge of $+Q$ is located at one of the corners of the square. What is the potential $($relative to infinity$)$ at the center when each of the other corners is also contains a point charge of $+Q?$

$43\mathrm{.}0$ V

B$)0$ V

$9\mathrm{.}0$ V

$($D$)2$ V