What Is the Main Purpose of Hot Swapping Technology in Disk

What is the main purpose of hot swapping technology in disk enclosures?

A) To be able to swap out the disks when the temperature is too hot.
B) To swap out the hard disks after proper shutdown of storage system.
C) Maintain the temperature of the disks to prevent overheating.
D) To swap out the hard disks without turning off the storage system.