The correct answer is C.
OBJ-4.5: The first thing that must be done after acquiring a forensic disk image is to create a hash digest of the source drive and destination image file to ensure they match. A critical step in the presentation of evidence will be to prove that analysis has been performed on an identical image to the data present on the physical media and that neither data set has been tampered with. The standard means of proving this is to create a cryptographic hash or fingerprint of the disk contents and any derivative images made from it. When comparing hash values, you need to use the same algorithm used to create the reference value. While encrypting the image files is a good security practice to maintain the data’s confidentiality, it does not provide data integrity like a hash digest does. Once imaged, the source drive should not be altered or encrypted. Digitally signing the image file could serve the function of non-repudiation, but it is an uncommon practice and not required to be performed.