The velocity of a particle in simple harmonic motion at displacement y from mean position is 

• A

  $\mathrm{\omega }\sqrt{{\mathrm{a}}^2+{\mathrm{y}}^2}$

• B

  $\mathrm{\omega }\sqrt{{\mathrm{a}}^2-{\mathrm{y}}^2}$

• C

  $\mathrm{\omega y}$

• D

  ${\mathrm{\omega }}^2\sqrt{{\mathrm{a}}^2-{\mathrm{y}}^2}$