a
Applying Kirchhoff law
$(2 + 2) = (0.1 + 0.3 + 0.2)i$ $ \Rightarrow $ $i = \frac{{20}}{3}\,A$
Hence potential difference across $A$
$ = 2 - 0.1 \times \frac{{20}}{3} = \frac{4}{3}\,V$ (less than $2\,V$)
Potential difference across $B = 2 - 0.3 \times \frac{{20}}{3} = 0$