For individuals over 40 years of age, how long is a class 1 medical valid for?

For individuals over 40 years of age, a Class 1 medical certificate is valid for a period of 12 months, which aligns with option A. The shorter durations in the other choices do not apply to the Class 1 medical certification; they are typically relevant to different classes of medical certifications or specific circumstances.

The validity duration is important for ensuring that pilots maintain a high standard of health necessary for the safety of themselves and others while flying. Regular medical assessments help monitor any changes in health that could impact a pilot's ability to operate an aircraft safely.