b
In the circuit drawn in currents allotted, apply Kirchoffs Voltage Law in first loop,
$2-2\left(i_{1}\right)+4-1\left(i_{1}\right)=0$
$\Longrightarrow i_{1}=2 A$
since there is no resistance or battery in branch $RQ,$ $V_{R}=V_{Q}$
$\Longrightarrow V_{P Q}=V_{P}-V_{Q}=V_{P}-V_{R}=-2 V+(2 \Omega)(2 A)=+2 V$
