I think its C.locate key Info Because if you reread the paragraph you will find some sentences that will help you.
1. Must Go to bed early.must not stay up late.
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2. Must Be polite.must not be rude
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3. Must not wear jeans. Must Wear smart clothes
4. Must Put your mobile on silent.must not disturb people on the train
5. Must Take off your shoes.must not make the carpet dirty
6.must not jump the queue.must Wait for your turn
Society would be very chaotic and full of mistrust as people will say things they didn’t mean to say. It is human nature to protect and not reveal certain thoughts.
Hope this helped!