The correct answer is B. FORMAT A: /Q.
The /Q switch tells DOS to perform a quick format. A quick format does not perform a check of the disk for bad sectors, and it does not write a volume label to the disk.
The /QUICK switch is a synonym for the /Q switch.
The /QU switch is not a valid switch.
The /QF switch is not a valid switch.
A quick format is a good option if you are sure that the disk is not damaged and you do not need to write a volume label to the disk.