The gas equation for $n$ moles of a real gas is, $\left[P+\frac{a}{V^2}\right]\left(V-b\right)=nRT$, where $P$ is the pressure, $V$ is the volume, $T$ is the absolute temperature, $R$ is the molar gas constant and $a\text{,} b$ are arbitrary constants. Which of the following has/have the same dimensions as that of $PV$?