For the rotor system shown in figure, the mass required for its complete balancing is

Question

         (a) 1.5 kg at 2 m radius and at  from reference

         (b) 3 kg at 1 m radius and at from reference

         (c) 8 kg at 1 m radius and at from reference

         (d) 4 kg at 2 m radius and at from reference