Choice "C" is correct. Just-in-time means that employees with multiple skills are used more efficiently and will not specialize in merely one job or task.
Choice "b" is incorrect. Just-in-time coordination of supplies inventory generally means synchronization of production scheduling with demand and supplies arrive at regular intervals throughout the production day.
Choice "a" is incorrect. Reduced set up times that no longer need to accommodate buffers for delivery of goods are benefits and features of just-in-time inventory systems.
Choice "d" is incorrect. Just-in-time requires a sense of empowerment amongst employees to ensure the coordination of production and materials delivery is handled with maximum efficiency and accommodates variable schedules.