$C=\frac{\varepsilon_{0} A}{d}$ $...(i)$
Also capacitance = potential difference$/$charge $.....(ii)$
When battery is disconnected and the distance between the plates of the capacitor is increased then capacitance increases and charge remains constant.
since capacitance $=$ potential difference$/$charge
$\therefore$ Potential difference increases.

Assertion $(A)$ and the other is labelled as Reason$(R)$
$Assertion$ $(A)$ : Work done by electric field on moving a positive charge on an equipotential surface is always zero.
$Reason$ $(R)$ : Electric lines of forces are always perpendicular to equipotential surfaces.
In the light of the above statements, choose the most appropriate answer from the options given below

