An airline should recognize revenue from airline tickets in the period when:

Option D  >>>>>>>>>>>>>>>>>>>>>    Related flights occur.

Thank you Sir for giving me opportunity..answer is Option D ) related flights occur.

D is correct.

When related flights occur.

D When the actual service occurs then the revenue is recognized and reduced from the liability they owe to the customer for the service that should be provided for a pre-purchased ticket

I would go for C, when tickets are issued. since it is the time payment has been done.

C is the correct one becuase when it issue once a ticket it can be cancel onely.

D. Related flights occur.

In other words, the airline industry measures a worth based on flown revenue.

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I think answer (C) may be correct here.