Here are my thoughts.. please give your rebuttals
1. why must it be a trap instruction? I find no reason that it has to be a trap. No referenced link in this post says it has to be a trap.
2. It has to be a privileged instruction because it accesses kernel stack in the newer OS. Although in older OS, there was no concept of kernel space and user space, it was one huge address space.
3. An exception cannot be allowed to occur? Aborts and faults (they are exceptions too) can occur during the execution of any instruction. It's like saying power failure is not allowed to happen when RFE is executing.
I think the answer should be II only