When considering the secure storage and accessibility of critical data such as the contents of the Operator CD, it is important to ensure physical and digital security measures are in place. Storing the CD in a physical safe and mounting it every time vault maintenance is performed provides a high level of physical security, preventing unauthorized access. Securing a copy of the CD's contents in a folder on the Vault Server with NTFS permissions ensures that access is controlled and only authorized personnel can access it. This balances both accessibility and security. The other options may introduce unnecessary complexity or may not provide the same level of security.