I would consider it more of a 'logic' problem.
Once you realise that there is no readily apparent answer, you need to analyse the question to see where the original premise is faulty.

A 'riddle', such as the riddle of the Sphinx, has an answer which may be logical, and which may be one of several possible correct answers, but seems to require a leap of understanding to arrive at the 'correct' answer.
No such leap of understanding will ever get you a valid answer to the question as set above.