Under what conditions may odometers be repaired or replaced?

Answer: C — Only if they become defective or malfunction

Odometers may only be repaired or replaced if they become defective or malfunction. This means that if the odometer is not functioning properly, it may be repaired or replaced. The other options, such as only after the vehicle is sold, only if authorized by the manufacturer, and only after an inspection by a certified technician, are incorrect because those conditions do not necessarily relate to the malfunction or defect of the odometer. For example, an odometer may need to be repaired or replaced before a vehicle is sold or without the authorization of the manufacturer, and a certified technician may not need to inspect it for it to be repaired or replaced. Therefore, these options do not accurately reflect the conditions under which odometers may be repaired or replaced.