A capacitor of capacitance is charged fully by
battery B as shown in fig (a). Then it is disconnected from the battery and connected to another uncharged capacitor of capacitance
as shown in fig(b). The electrostatic energy stored by system (b) is :


( charged capacitor just connected (Steady state )
to uncharged capacitor )
As both the capacitor are in a parallel connection they attained the same potential at the steady state
Common potential
Hence the correct option is 2