Two masses ${\mathrm{m}}_1$ and ${\mathrm{m}}_2$ are suspended together by a massless spring of constant k. When the masses are in equilibrium, ${\mathrm{m}}_1$ is removed without disturbing the system. Then the angular frequency of oscillation of ${\mathrm{m}}_2$ is

• A

  $\sqrt{\frac{\mathrm{k}}{{\mathrm{m}}_1}}$

• B

  $\sqrt{\frac{\mathrm{k}}{{\mathrm{m}}_2}}$

• C

  $\sqrt{\frac{\mathrm{k}}{{\mathrm{m}}_1+{\mathrm{m}}_2}}$

• D

  $\sqrt{\frac{\mathrm{k}}{{\mathrm{m}}_1{\mathrm{m}}_2}}$