The equation of a state of gas is given by $PV = nRT + Pb$. If the gas is isothermally expanded from a volume $V$ to $2V$, what is the work done during the process?

Question

(A) $nRT \log \frac{2Vb}{V-b}$ (B) $nRT \log \frac{V-b}{2V-b}$ (C) $nRT \log \frac{2V-b}{V-b}$ (D) $nRT \log \frac{2V}{V-b}$