As you can see from the diagram, AD and AC are in series. Similarly, BD and BC are in series. In effect, the two series combinations are in parallel. The effective resistance of each branch (2 + 3 =5, and 3+2 =5) is 5 ohm each. Since the resistance of each branch from D to C is 5 ohm, the current divides equally among the branches. Thus the current in each is 2.5 A.
The potential difference across, DA = 2.5 x 2 = 5 V
The potential difference across, DB = 3 x 2 = 6 V
The potential difference between A & B = 6-5 = 1 V