CPU Bound process means , the process which do not perform large I/O are CPU bound process, as those process spend most of their execution time in solving the problem in cpu rather than involving in reading/writing. CPU bound process would go faster if the CPU were faster.
RR is pre emptive .
FCFS is Non pre emptive .
Multilevel feedback queue is also pre emptive .
Now, preemption means there is a interrupt that implies number of I/O is high so preemptive process can not be CPU bound .
so option A, option D can not be possible as both deals with pre emptive process.
option C also can not be possible as it combines both RR and FCFS means combine both pre emptive and non preemptive.
FCFS is cpu bound as it is non pre emptive so number of I/O operation is none.
so only option B is correct .