Damping factor and damped natural frequency of a vehicular suspension system

Question

1. A vehicle suspension system consists of a spring and a damper. The stiffness of the spring is 3.6 kN/m and the damping constant of the damper is 400 Ns/m. If the mass is 50 kg, then the damping factor (x) and damped natural frequency (f_n) respectively are                                                                                                

(a) 0.47 and 1.19 Hz

(b) 0.471 and 7.48 Hz

(c) 0.666 and 1.35 Hz

(d) 0.666 and 8.50 Hz