As there is no current through AB, all the points of AB are at the same potential, say V1. For the same reason, all the points of CD are at the same potential, say V2. But V1 > V2 because current is flowing from A to C or B to D. Therefore, VE > VF. This is why on connecting E and F by a wire, current will flow from E to F.
Hence choice (2) is correct.