When a mass $\mathrm{m}$ is suspended from the free end of a massless spring having force constant $\mathrm{k}$, its oscillates with frequency $\mathrm{f}$. Now if the spring is divided into two equal parts and a mass $2 \mathrm{~m}$ is suspended from the end of anyone of them, it will oscillate with a frequency equal to.........
(A) $\mathrm{f}$
(B) $2 \mathrm{f}$
(C) $(\mathrm{f} / \sqrt{2})$
(D) $\sqrt{2 f}$