Modern operating systems $($e$.$g$.,$ Linux, Windows, MacOS$)$ control access to protected resources to ensure proper execution of applications that may belong to different users. The following is an example of such a protected resource.

Group of answer choices

main memory pages.

files that store user data.

physical devices.

All of the above. Modern processor architectures are aware when they are executing instructions from the operating system or user code. The reason for distinguishing if the code being executed belongs to the operating system or to a user application is

Group of answer choices

operating system code can execute certain instructions that cannot be executed by user code.

user and system code can execute all instructions.

user code is not allowed to execute any instructions..

operating system code cannot execute many instructions that are available to user code.