Final answer:
The removal of Peter's monitor likely represents the lifting of restraints on his actions, which correlates with the philosophical idea that such a change could lead to unrestricted behavior, such as violence.
Step-by-step explanation:
The question asks why the removal of the monitor made Peter more dangerous. Assuming that this question is related to a literary or philosophical context, likely the removal of a figurative 'monitor' implies that Peter no longer has a safeguard or a check to his actions, which can make the person act without restraint or consideration of consequences. This concept can be related to the philosophical dialogue between Socrates and Glaucon, where the removal of the prisoner from the cave (analogous to the removal of a monitor) leads to a period of adjustment where his perception is heightened, demonstrating the change an individual undergoes when restrictions are lifted. Therefore, the most accurate answer would be C) He could now engage in unrestricted violence.