How would you permanently erase the data on the hard disk?

You have completed a forensic investigation case. You would like to destroy the data contained in various disks at the forensics lab due to sensitivity of the case. How would you permanently erase the data on the hard disk?

A.
Throw the hard disk into the fire

B.
Run the powerful magnets over the hard disk

C.
Format the hard disk multiple times using a low level disk utility

D.
Overwrite the contents of the hard disk with Junk data