Mark the correct statement:

When a stationary wave is established in a medium then maximum deformation of the medium is produced at nodes. Hence, maximum pressure change takes place at nodes and at antinodes, no pressure change takes place. Therefore, option (a) is wrong.$v=\sqrt{\frac{Elasticity}{Density}}$. Since, elasticity and density both are the characteristic property of the medium, therefore, velocity of a longitu­dinal wave in a medium is its physical characteristic. So, option (b) is correct. Due to propagation of longitudinal wave in a medium pressure change $\Delta P=\frac{\gamma Pu}{v}$ where u is the velocity of medium particles. Pressure change will be maximum possible when me­dium particles have maximum possible velocity, which is equal to aw = 2pna. $∆P=2\pi na\rho v$. So, option (c) and therefore option (d) is also wrong.