From question it seems like none of the above:
i) File descriptor table
File descriptor tables store the information about which files are currently open. They are not bound to a particular process but have a global presence. This is useful in the case when one process tries to delete a file when it is being used by another process. There is really no point of keeping this in the user table.
ii) System call state
Processes makes system calls to the kernel to get some special "privileged " service from the kernel for which processes cannot be trusted like reading from disk, memory management etc. Again no point keeping this in the user table as these are specific to process.
iii) Scheduling parameters
Process are scheduled not users. May if there is some concept whether user A has high priority than user B then this infomration can be stored into the user table but I am not so sure if that is how priority is handled in the kernel.
iv)Kernel stack
Kernel stack is the stack used by the kernel when its executing a system call or handling the interrupt on behalf of the process which was actually running on the processor. This is definitely not stored on the user structure.
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Is this correct.. or am I totally wrong? This needs discussion.