The natural frequency of the uniform rigid rod supported by springs

Question

A rigid uniform rod AB of length L and mass m is hinged at C such that AC = L/3, CB = 2L/3. Ends A and B are supported by springs of spring constant k. The natural frequency of the system is given by                                                                                                                                            

(a) $\sqrt{\frac{k}{2m}}$                                                               (b) $\sqrt{\frac{k}{m}}$ 

(c) $\sqrt{\frac{2k}{m}}$                                                               (d) $\sqrt{\frac{5k}{m}}$