Mode transfer $($from user mode to kernel mode$)$ can happen via three mechanisms system calls, $($hardware$)$ interrupts, or exceptions$/$faults$.$ For each scenario listed below, indicate which mechanism is most likely to be involved and in one sentence describe what will happen straight after the mode transfer. i$)$ A timer indicates that a different process may need to be scheduled. ii$)$ An external I$/$O device signals the completion of an I$/$O request. iii$)$ A user process attempts to access memory it does not have access to$.$ iv$)$ A user process invokes a function to kill another process.