A particle of mass $m$ is attached to three identical springs $A, B$ and $C$ each of force constant $k$ as shown in figure. If the particle of mass $m$ is pushed slightly against the spring $A$ and released, then the time period of oscillation is
(a) $2 \pi \sqrt{\frac{2 m}{k}}$
(b) $2 \pi \sqrt{\frac{m}{2 k}}$
(c) $2 \pi \sqrt{\frac{m}{k}}$
(d) $2 \pi \sqrt{\frac{m}{3 k}}$