I think this question could be done by option elimination method:
Since b and d are the same hence they both cannot be the answer as multiple options not allowed.
Now, superuser mode is a mode that requires an administrator to do certain tasks.
Now think of a situation when you are using a computer in guest mode. Now you have written an infinite loop program and running in cmd. Now to stop cmd you will press ctrl+c and immediately the program stops without asking any permission. Now, this means CPU does not ask you for admin permission to do ctrl+c. This means the task can be done without going superuser mode.
Now, you have only one option left. Hence, A will be the answer.
Please correct if I'm wrong.