Equation of sound wave propagating in still air is $\mathrm{y}=a \sin \left(\mathrm{\omega t}-\mathrm{Kx}\right)$. Then the equation of pressure wave propagating in the same medium is of the form

• A

  $\mathrm{p}={\mathrm{p}}_{\mathrm{m}} \cos \left(\mathrm{\omega t}+\mathrm{Kx}\right)$

• B

  $\mathrm{p}={\mathrm{p}}_{\mathrm{m}} \sin \left(\mathrm{\omega t}-\mathrm{Kx}\right)$

• C

  $\mathrm{p}={\mathrm{p}}_{\mathrm{m}} \cos \left(\mathrm{\omega t}-\mathrm{Kx}\right)$

• D

  $\mathrm{p}={\mathrm{p}}_{\mathrm{m}} \sin \left(\mathrm{\omega t}+\mathrm{Kx}\right)$