The deviations from ideal gas (pV=nRT) depend on the temperature pressure and nature of gas. Among all options, NH3 is the one which show maximum deviation under the same conditions. NH3 will show maximum deviation from ideal gas due to more dipole-dipole attractions which leads to more attractive forces between molecules of NH3. In NH3 there are strong intermolecular force of attraction, so the van der Waals' constant value is high.