In_a_lifting_machine,_the_effort_required_to_lift_loads_of_200N_and_300N_were_50N_and_60N_respectively._If_the_velocity_ratio_of_the_machine_is_20_determine_maximum_efficiency_which_can_be_expected_from_this_machine.$

• A. 30 %
• B. 40 %
• C. 50 %
• D. 60 %