When using a mechanical (windup type) marine chronometer, how often should it be reset?

Correct Answer: Option C — Only when it is overhauled

Mechanical marine chronometers are precision instruments designed to maintain a consistent rate. They should never be reset by the navigator, as this disrupts the established rate and error record. Any necessary adjustments or resetting must only be performed by a qualified horologist during a professional overhaul to maintain navigational integrity.