b
For ideal gas

\(P V=n R T\)

\(P V=\frac{m}{M} R T\)

\(P=\left(\frac{M}{V}\right) \frac{R T}{M}\)

\(P=\frac{\rho R T}{M}\)

(Where \(\mathrm{m}\) is mass of gas and \(\mathrm{M}\) is molecular mass of gas)

for same temperature \(\mathrm{P}_1>\mathrm{P}_2>\mathrm{P}_3\)

So \(\rho_1>\rho_2>\rho_3\)

So correct answer is \((2)\)