How to solve

A parallel$-$plate capacitor is situated with the positive plate on the left and the negative plate on the right carrying equal and opposite charges $(Q$ and $-Q),$ and having equal areas $A=R^2.$ The plates are separated by a distance $sR.$ Points $A,B,C,$ and D are at the corners of a rectangle with sides $h=4\mathrm{.}8mm$ and $w=2\mathrm{.}5mm.$ Assume all four points are far from the edge of the capacitor so that the electric field is uniform. If the magnitude of the electric field is $E=760\frac{V}{m},$ what's the potential difference $V=V_B-V_C?$

$1\mathrm{.}90$ V

$-4\mathrm{.}11$ V

$-1\mathrm{.}90$ V

$4\mathrm{.}11$ V

The correct answer is $-1\mathrm{.}90$V$.$

Please show me how to reach this.