What is a key feature of File Sanitizer for HP ProtectTools?

A.
free space bleaching

B.
encrypted hard drive support

C.
BIOS level security checks

D.
multi-factor file security

Explanation:
http://h20331.www2.hp.com/hpsub/cache/281822-0-0-225-121.html?jumpid=ex_2845_vanitysecur/productssecurity/ka011106#9(file sanitizer, click More info)