Question Statement :

The news that Richard W. Matt, the convicted murderer who was killed by the police on Friday after a weeks-long manhunt, spent most of his time behind bars painting technically skilled portraits of Julia Roberts, President Obama and fellow inmates’ relatives, and bartering them for preferential treatment, has come as a surprise to many. But to those who have spent years teaching art in prisons or making it themselves as inmates, such a trade is a deeply ingrained ritual of incarcerated life. It is practiced informally or as part of established programs by a wide range of prisoners, many of them, like Mr. Matt, with profoundly violent pasts and little art experience.

Which of the following can best be inferred from this passage?