I would say that saying they’re imprisoned because of criminal activity is answering the question. It’s hardly a secret, it has been detailed in the news that the prisoners are jailed for crimes like attempted stabbings, handling explosives, arson and throwing rocks. Some are more minor than others, but all are crimes and would be considered crimes elsewhere. Expecting Israel not to criminalise those, including juveniles, is holding them to a different standard as any other country (including ourselves, who would imprison anyone for any of these things). I do have to question why the hideous crime of Israel imprisoning those for committing crimes is evil when it isn’t for anyone else, unless the argument is that the UK and other countries should decriminalise assault, arson and attempted murder.