As far as maintenance costs are concerned: Part 2 A. for low levels of maintenance commitment, preventive maintenance costs exceed breakdown maintenance costs. B. for low levels of maintenance commitment, breakdown maintenance costs exceed preventive maintenance costs. C. preventive maintenance is always more economical than breakdown maintenance. D. breakdown maintenance is always more economical than preventive maintenance when the "full cost of breakdowns" is taken into consideration. E. for high levels of maintenance commitment, breakdown maintenance costs exceed preventive maintenance costs