The correct answer is that maintaining an accurate hash is necessary because it verifies that the forensic image has not been tampered with since it was acquired. This is crucial for preserving the integrity of digital evidence. If the hash value changes, it indicates that the image might have been altered, which can compromise the evidence. Other answers might seem plausible, but the focus on the hash is specific to the integrity verification process and not directly related to aspects like encryption or access controls, which although important, do not serve the same purpose.