Correct Answer Is:-
A) nkx
To find out when the first process will complete its execution, we need to consider the total time required for all processes to complete and then determine when the first process will finish.
Each process requires kx seconds to complete, and there are n processes in the ready queue. Therefore, the total time required for all processes to complete is nkx seconds.
Since the scheduling is round-robin, the first process will complete its execution after one complete cycle through all processes. In each cycle, each process gets a time quantum x to execute. Therefore, the first process will complete its execution after nx seconds.