A machine of 100 kg mass has 20 kg rotor with 0.5 mm eccentricity. The mounting springs have stiffness 85 kN/m and damping is negligible. If the operating speed is 20 $\pi$rad/s and the unit is constrained to move vertically, the dynamic amplitude of the machine will be
(a) 0.470 $\times$ 10–4 m (b) 1.0 $\times$ 10–4 m
(c) 1.270 $\times$ 10–4 m (d) 2.540 $\times$ 10–4 m