What exactly is John trying to do?

John Beetlesman, the hacker has successfully compromised the Linux system of Angent Telecommunications, Inc’s?Webserver running Apache. He has downloaded sensitive documents and database files off the machine.

Upon performing various tasks, Beetlesman finally runs the following command on the Linux box before disconnecting.

for (( i = 0;i<11;i++ )); do
?dd if=/dev/random of=/dev/hda && dd if=/dev/zero of=/dev/hda done

What exactly is John trying to do?

A.
He is making a bit stream copy of the entire hard disk for later download

B.
He is deleting log files to remove his trace

C.
He is infecting the hard disk with random virus strings

D.
He is wiping the contents of the hard disk with zeros

Explanation:
dd copies an input file to an output file with optional conversions. – if is input file, -of is output file. /dev/zero is a special file that provides as many null characters (ASCII NULL, 0x00; not ASCII character “digit zero”, “0”, 0x30) as are read from it. /dev/hda is the hard drive.