The correct option is B + 1V
In the given circuit 2A current divides equally at junction D along the paths DAC and DBC (each path carry 1A current).
Potential difference between D and A, VD−VA=1×2=2 volt .......(i)
Potential difference between D and B, VD−VB=1×3=3 volt .......(ii)
On solving (i) and (ii) VA−VB=+1 volt