A- Like always choose more distance from itself , so it can't be answer
B- its SSTF
C- its FCFS
D-Its SCAN
> FCFS throughput is less then SSTF so it's also not answer
> now the fight b//w SSTF and SCAN
SSTF always serve nearest cylinder first , so necessary movements gets reduced . and in case of SCAN it goes to one end and come back ,which takes more time to complete task , so SSTF throughput is best .