What Technique Used by Encase Makes It Virtually Impossible to Tamper

What technique used by Encase makes it virtually impossible to tamper with evidence once it has been acquired?

A) Every byte of the file(s) is given an MD5 hash to match against a master file
B) Every byte of the file(s) is verified using 32-bit CRC
C) Every byte of the file(s) is copied to three different hard drives
D) Every byte of the file(s) is encrypted using three different methods