Chronic fatigue can be caused by

Chronic fatigue is a complex condition that can stem from various factors, including those outlined in the question. The correct answer encompasses a broader understanding of the causes of chronic fatigue.

Extended sleep can sometimes lead to feelings of grogginess or lethargy, particularly if it disrupts the natural circadian rhythm. However, the quality of sleep is more critical than the quantity, and merely sleeping longer does not ensure that one feels rested.

Normal daily activities, while generally necessary for physical and mental well-being, can gradually lead to fatigue if they are excessive or not balanced with appropriate rest and recovery. This is particularly true for crewmembers in high-pressure environments where consistent alertness is required.

Psychological stress is a well-established contributor to chronic fatigue. It can lead to mental exhaustion and diminish one's ability to manage physical tasks efficiently. The impact of psychological stress is profound, as it not only affects energy levels but can also interfere with sleep quality, creating a vicious cycle.

The most comprehensive understanding reflects that chronic fatigue can originate from a combination of inadequate recovery from normal activities, psychological stress, and sleep patterns, making the option that includes all factors the most accurate.