Why is the question of "how easily people can get used to working at night" no mere academ

Why is the question of "how easily people can get used to working at night" no mere academic one？

A．Because few people like to reverse the cycle of sleep and wakefulness.

B．Because sleep normally coincides with the hours of darkness.

C．Because people are required to work at night in some fields of industry.

D．Because shift work in industry requires people to change their sleeping habits.

请帮忙给出正确答案和分析，谢谢！