Two moles of an ideal gas at $300\mathrm{K}$ expand freely (into vacuum, adiabatic walls) from $5.0\mathrm{L}$ to $15.0\mathrm{L}$. The gas is then compressed reversibly and isothermally at $300\mathrm{K}$, with heat exchanged with the surroundings, back to $5.0\mathrm{L}$. Using $R=8.314\mathrm{J}\mathrm{mo}{\mathrm{l}}^{-1}{\mathrm{K}}^{-1}$, the values of $\Delta S_{sys}$ and $\Delta S_{surr}$ for the complete two-step process are

1. A$+18.27$ and $0\mathrm{J}{\mathrm{K}}^{-1}$
2. B$0$ and $0$
3. C$+18.27$ and $+18.27\mathrm{J}{\mathrm{K}}^{-1}$
4. D$0$ and $+18.27\mathrm{J}{\mathrm{K}}^{-1}$